Golf club

ABSTRACT

A golf club head includes a golf club body including a crown, a sole, and a skirt connected between the crown and the sole, the golf club body including a front including a leading edge and a back including a trailing edge, and a hosel connected to the golf club body; a face connected to the front of the golf club body, the face including a geometric center, the golf club head including reduced spin on various shots.

REFERENCE TO RELATED APPLICATIONS

This application incorporates by reference the following United Statespatents and United States patent application: U.S. Patent ApplicationNo. 62/027,692, filed on Jul. 22, 2014, and entitled “GOLF CLUB,” whichis incorporated by reference herein in its entirety. This applicationreferences application for U.S. patent bearing Ser. No. 13/839,727,entitled “GOLF CLUB WITH COEFFICIENT OF RESTITUTION FEATURE,” filed Mar.15, 2013, which is incorporated by reference herein in its entirety andwith specific reference to discussion of center of gravity location andthe resulting effects on club performance. This application alsoreferences U.S. Pat. No. 7,731,603, entitled “GOLF CLUB HEAD,” filedSep. 27, 2007, which is incorporated by reference herein in its entiretyand with specific reference to discussion of moment of inertia. Thisapplication also references U.S. Pat. No. 7,887,431, entitled “GOLFCLUB,” filed Dec. 30, 2008, which is incorporated by reference herein inits entirety and with specific reference to discussion of adjustableloft and lie technology described therein and with reference toremovable shaft technology and hosel sleeve connection systems. Thisapplication also references application for U.S. patent bearing Ser. No.13/718,107, entitled “HIGH VOLUME AERODYNAMIC GOLF CLUB HEAD,” filedDec. 18, 2012, which is incorporated by reference herein in its entiretyand with specific reference to discussion of aerodynamic golf clubheads. This application also references U.S. Pat. No. 7,874,936,entitled “COMPOSITE ARTICLES AND METHODS FOR MAKING THE SAME,” filedDec. 19, 2007, which is incorporated by reference herein in its entiretyand with specific reference to discussion of composite face technology.This application also references application for U.S. patent bearingSer. No. 14/144,105, entitled “GOLF CLUB,” filed Dec. 30, 2013, which isincorporated by reference herein in its entirety and with specificreference to discussion of moment of inertia, center of gravityplacement, and the effect of center of gravity placement on mechanics ofgolf club heads. This application also references application for U.S.patent bearing Ser. No. 12/813,442, entitled “GOLF CLUB,” filed Jun. 10,2010, which is incorporated by reference herein in its entirety and withspecific reference to discussion of variable face thickness. Thisapplication references application for U.S. patent bearing Ser. No.12/791,025, entitled “HOLLOW GOLF CLUB HEAD,” filed Jun. 1, 2010, andapplication for U.S. patent bearing Ser. No. 13/338,197, entitled“FAIRWAY WOOD CENTER OF GRAVITY PROJECTION,” filed Dec. 27, 2011, whichare incorporated by reference herein in their entirety and with specificreference to slot technology and coefficient of restitution features.This application also references U.S. Pat. No. 6,773,360, entitled “GOLFCLUB HEAD HAVING A REMOVABLE WEIGHT,” filed Nov. 8, 2002, which isincorporated by reference herein in its entirety and with specificreference to discussion of removable weight. This application alsoreferences U.S. Pat. No. 7,166,040, entitled “REMOVABLE WEIGHT AND KITFOR GOLF CLUB HEAD,” filed Feb. 23, 2004, which is acontinuation-in-part of U.S. Pat. No. 6,773,360, entitled “GOLF CLUBHEAD HAVING A REMOVABLE WEIGHT,” and which is incorporated by referenceherein in its entirety and with specific reference to removable weighttechnology.

TECHNICAL FIELD

The current disclosure relates to golf club heads. More specifically,the current disclosure relates to golf club heads with features forimproving playability, including at least one of relocation of center ofgravity and coefficient of restitution features.

SUMMARY

A golf club head includes a golf club body including a crown, a sole,and a skirt connected between the crown and the sole, the golf club bodyincluding a front including a leading edge and a back including atrailing edge, and a hosel connected to the golf club body; a faceconnected to the front of the golf club body, the face including ageometric center, the golf club head including reduced spin on variousshots.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and components of the following figures are illustrated toemphasize the general principles of the present disclosure.Corresponding features and components throughout the figures may bedesignated by matching reference characters for the sake of consistencyand clarity.

FIG. 1A is a toe side view of a golf club head in accord with oneembodiment of the current disclosure.

FIG. 1B is a face side view of the golf club head of FIG. 1A.

FIG. 1C is a perspective view of the golf club head of FIG. 1A.

FIG. 1D is a top view of the golf club head of FIG. 1A.

FIG. 2 is a cross-sectional view of the golf club head taken in theplane indicated by line 2-2 of FIG. 1D.

FIG. 3 is a detail view of detail 3 of FIG. 2.

FIG. 4 is a bottom view of the golf club head of FIG. 1A.

FIG. 5 is a bottom perspective view of a golf club head in accord withone embodiment of the current disclosure.

FIG. 6A is a heel side view of the golf club head of FIG. 5.

FIG. 6B is a face side view of the golf club head of FIG. 5.

FIG. 7 is a cross-sectional view of the golf club head taken in theplane indicated by line 7-7 of FIG. 6B.

FIG. 8 is a close-up view of detail 8 in FIG. 7.

FIG. 9 is a cross-sectional view of the golf club head taken in theplane indicated by line 9-9 in FIG. 6A.

FIG. 10 is a bottom perspective view of a golf club head in accord withone embodiment of the current disclosure.

FIG. 11A is a heel side view of the golf club head of FIG. 10.

FIG. 11B is a face side view of the golf club head of FIG. 10.

FIG. 11C is a top side view of the golf club head of FIG. 10.

FIG. 12 is a cross-sectional view of the golf club head taken in theplane indicated by line 12-12 in FIG. 11A.

FIG. 13 is a cross-sectional view of the golf club head taken in theplane indicated by line 13-13 in FIG. 11C.

FIG. 14 is a cross-sectional view of the golf club head taken in theplane indicated by line 14-14 in FIG. 11A.

FIG. 15 is a bottom perspective view of a golf club head in accord withone embodiment of the current disclosure.

FIG. 16 is a cross-sectional view of the golf club head taken in theplane indicated by line 16-16 in FIG. 15.

FIG. 17 is a bottom perspective view of a golf club head in accord withone embodiment of the current disclosure.

FIG. 18 is a detail cross-sectional view of the golf club head taken inthe plane indicated by line 18-18 in FIG. 17.

FIG. 19 is a heel side view of the golf club head of FIG. 17.

FIG. 20A is a plot showing COR values related to a reference club.

FIG. 20B is a plot showing COR values related to a golf club head inaccord with one embodiment of the current disclosure.

FIG. 20C is a plot showing COR values related to a golf club head inaccord with one embodiment of the current disclosure.

FIG. 21 is a golf club head in accord with one embodiment of the currentdisclosure including a loft sleeve.

FIG. 22A is a top side view of a plug in accord with one embodiment ofthe current disclosure.

FIG. 22B is a front side view of the plug of FIG. 22A.

FIG. 22C is a left side view of the plug of FIG. 22A.

FIG. 22D is a perspective view of the plug of FIG. 22A.

DETAILED DESCRIPTION

Disclosed is a golf club including a golf club head and associatedmethods, systems, devices, and various apparatus. It would be understoodby one of skill in the art that the disclosed golf club is described inbut a few exemplary embodiments among many. No particular terminology ordescription should be considered limiting on the disclosure or the scopeof any claims issuing therefrom. For the sake of simplicity, standardunit abbreviations may be used, including but not limited to, “mm” formillimeters, “in.” for inches, “lb.” for pounds force, “mph” for milesper hour, and “rps” for revolutions per second, among others.

Portions of the following disclosure are coincident with application forU.S. patent bearing Ser. No. 13/839,727, entitled “GOLF CLUB WITHCOEFFICIENT OF RESTITUTION FEATURE,” filed Mar. 15, 2013, which isincorporated by reference herein in its entirety. Although portions ofthe disclosure have been omitted from the current disclosure in theinterest of efficiency, one of skill in the art would understand thatthe features and designs disclosed in the referenced application wouldapply to the descriptions of the technology of the current disclosure,and the full incorporation of application for U.S. patent bearing Ser.No. 13/839,727 is beneficial for a complete understanding of the scopeof the current disclosure. Additionally, claimed subject matter mayinclude features or descriptions supplied in more full detail by theincorporation of application for U.S. patent bearing Ser. No.13/839,727, and claims covering content in the reference application arerelated to the disclosure such application.

In the game of golf, when a player increases his or her distance with agiven club, the result nearly always provides an advantage to theplayer. While golf club design aims to maximize the ability of a playerto hit a golf ball as far as possible, the United States GolfAssociation—a rulemaking body in the game of golf—has provided a set ofrules to govern the game of golf. These rules are known as The Rules ofGolf and are accompanied by various Decisions on The Rules of Golf. Manyrules promulgated in The Rules of Golf affect play. Some of The Rules ofGolf affect equipment, including rules designed to indicate when a clubis or is not legal for play. Among the various rules are maximum andminimum limits for golf club head size, weight, dimensions, and variousother features. For example, no golf club head may be larger than 460cubic centimeters in volume. No golf club face may have a coefficient ofrestitution (COR) of greater than 0.830, wherein COR describes theefficiency of the golf club head's impact with a golf ball.

COR is a measure of collision efficiency. COR is the ratio of thevelocity of separation to the velocity of approach. In this model,therefore, COR is determined using the following formula:

COR=(ν_(club-post)−ν_(ball-post))÷(ν_(ball-pre)−ν_(club-pre))

where,

-   -   ν_(club-post) represents the velocity of the club after impact;    -   ν_(ball-post) represents the velocity of the ball after impact;

ν_(club-pre) represents the velocity of the club before impact (a valueof zero for USGA COR conditions); and

-   -   ν_(ball-pre) represents the velocity of the ball before impact.

Although the USGA specifies the limit for maximum COR, there is nospecified region in which COR may be maximized. While multiple golf clubheads have achieved the maximum 0.830 COR, the region in which such CORmay be found has generally been limited—typically, in a region at ageometric center of the face of the golf club head or in a region ofmaximum COR that is in relatively small proximity thereto. Many golfclub heads are designed to launch a golf ball as far as possible withinThe Rules of Golf when properly struck. However, even the greatest ofprofessional golfers do not strike each and every shot perfectly. Forthe vast majority of golfers, perfectly struck golf shots are anexception if not a rarity.

There are several methods to address a particular golfer's inability tostrike the shot purely. One method involves the use of increased Momentof Inertia (MOI). Increasing MOI prevents the loss of energy for strikesthat do not impact the center of the face by reducing the ability of thegolf club head to twist on off-center strikes. Particularly, mosthigher-MOI designs focus on moving weight to the perimeter of the golfclub head, which often includes moving a center of gravity of the golfclub head back in the golf club head, toward a trailing edge.

Another method involves use of variable face thickness (VFT) technology.With VFT, the face of the golf club head is not a constant thicknessacross its entirety, but rather varies. For example, as described inapplication for U.S. patent bearing Ser. No. 12/813,442, entitled “GOLFCLUB,” filed Jun. 10, 2010—which is incorporated herein by reference inits entirety—the thickness of the face varies in an arrangement with adimension as measured from the center of the face. This allows the areaof maximum COR to be increased as described in the reference.

While VFT is excellent technology, it can be difficult to implement incertain golf club designs. For example, in the design of fairway woods,the height of the face is often too small to implement a meaningful VFTdesign. Moreover, there are problems that VFT cannot solve. For example,edges of the golf club face tend to be more rigid than the center of thegolf club face because the edges include connection features to thesole, crown, or skirt of the golf club head. Because the edges of thetypical golf club face are integrated (either through a weldedconstruction or as a single piece), a strike that is close to an edge ofthe face necessarily results in poor COR as it is proximate the rigidedge. It is common for a golfer to strike the golf ball at a location onthe golf club head other than the center of the face. Typical locationsmay be high on the face or low on the face for many golfers. Bothsituations result in reduced COR. However, particularly with low facestrikes, COR decreases very quickly. In various embodiments, the COR forstrikes 5 mm below center face may be 0.020 to 0.035 difference. Furtheroff-center strikes may result in greater COR differences.

To combat the negative effects of off-center strikes, certain designshave been implemented. For example, as described in application for U.S.patent bearing Ser. No. 12/791,025, entitled “HOLLOW GOLF CLUB HEAD,”filed Jun. 1, 2010, and application for U.S. patent bearing Ser. No.13/338,197, entitled “FAIRWAY WOOD CENTER OF GRAVITY PROJECTION,” filedDec. 27, 2011—both of which are incorporated by reference herein intheir entirety—coefficient of restitution features located in variouslocations of the golf club head provide advantages. In particular, forstrikes low on the face of the golf club head, the coefficient ofrestitution features allow greater flexibility than would typically beseen otherwise from a region low on the face of the golf club head. Ingeneral, the low point on the face of the golf club head is not flexibleand, although not entirely rigid, does not experience the COR that maybe seen in the geometric center of the face.

Although coefficient of restitution features allow for greaterflexibility, they can often be cumbersome to implement. For example, inthe designs above, the coefficient of restitution features are placed inthe body of the golf club head but proximal to the face. While the closeproximity enhances the effectiveness of the coefficient of restitutionfeatures, it creates challenges from a design perspective. Manufacturingthe coefficient of restitution features may be difficult in someembodiments. Particularly with respect to application for U.S. patentbearing Ser. No. 13/338,197, entitled “FAIRWAY WOOD CENTER OF GRAVITYPROJECTION,” filed Dec. 27, 2011, the coefficient of restitution featureincludes a sharp corner at the vertical extent of the coefficient ofrestitution feature that experiences extremely high stress under impactconditions. It may become difficult to manufacture such features withoutcompromising their structural integrity in use. Further, the coefficientof restitution features necessarily extend into the golf club body,thereby occupying space within the golf club head. The size and locationof the coefficient of restitution features may make mass relocationdifficult in various designs, particularly when it is desirous to locatemass in the region of the coefficient of restitution feature.

In particular, one challenge with current coefficient of restitutionfeature designs is the ability to locate the center of gravity (CG) ofthe golf club head proximal to the face. As described in application forU.S. patent bearing Ser. No. 13/839,727, entitled “GOLF CLUB WITHCOEFFICIENT OF RESTITUTION FEATURE,” filed Mar. 15, 2013 and applicationfor U.S. patent bearing Ser. No. 14/144,105, entitled “GOLF CLUB,” filedDec. 30, 2013, it has been discovered that it is desirous to locate theCG low in the golf club head. Such location of CG provides a lowprojection of CG onto the face of the golf club head, which results inreduced spin, leading to greater distance. In certain types of heads, itmay still be the most desirable design to locate the CG of the golf clubhead as low as possible regardless of its location within the golf clubhead. However, for reasons explained in the references cited, it hasunexpectedly been determined that a low and forward CG location mayprovide some benefits not seen in prior designs or in comparable designswithout a low and forward CG.

For reference, within this disclosure, reference to a “fairway wood typegolf club head” means any wood type golf club head intended to be usedwith or without a tee. For reference, “driver type golf club head” meansany wood type golf club head intended to be used primarily with a tee.In general, fairway wood type golf club heads usually have lofts ofgreater than 14 degrees. In general, driver type golf club heads havelofts of 14 degrees or less, and, more usually, 12 degrees or less. Ingeneral, fairway wood type golf club heads have a length from leadingedge to trailing edge of 73-97 mm. Various definitions distinguish afairway wood type golf club head form a hybrid type golf club head,which tends to resemble a fairway wood type golf club head but be ofsmaller length from leading edge to trailing edge. In general, hybridtype golf club heads are 38-73 mm in length from leading edge totrailing edge. Hybrid type golf club heads may also be distinguishedfrom fairway wood type golf club heads by weight, by lie angle, byvolume, and/or by shaft length. Fairway wood type golf club heads of thecurrent disclosure preferably are 16 degrees of loft. In variousembodiments, fairway wood type golf club heads of the current disclosuremay be from 15-19.5 degrees. In various embodiments, fairway wood typegolf club heads of the current disclosure may be from 13-17 degrees. Invarious embodiments, fairway wood type golf club heads of the currentdisclosure may be from 13-19.5 degrees. In various embodiments, fairwaywood type golf club heads of the current disclosure may be from 13-26degrees. Additionally, most fairway wood type golf club heads arebetween 150 cc and 250 cc in volume as measured according to methods ofthe USGA. See U.S.G.A. “Procedure for Measuring the Club Head Size ofWood Clubs,” Revision 1.0.0, Nov. 21, 2003, for the methodology tomeasure the volume of a wood-type golf club head. Exemplary fairway woodtype golf club heads of the current disclosure may be between 180 cc and240 cc. In various embodiments, fairway wood type golf club heads of thecurrent disclosure are between 200 cc and 220 cc. Driver type golf clubheads of the current disclosure preferably are 12 degrees or less ofloft in various embodiments. Driver type golf club heads of the currentdisclosure may be 10.5 degrees or less in various embodiments. Drivertype golf club heads of the current disclosure may be between 9 degreesand 14 degrees of loft in various embodiments. In various embodiments,driver type golf club heads may be as much as 16 degrees of loft.Additionally, most driver-type golf club heads are over 375 cc involume. Exemplary driver-type golf club heads of the current disclosuremay be over 425 cc in volume. In some embodiments, driver-type golf clubheads of the current disclosure are between 440 cc and 460 cc in volume.

One embodiment of a golf club head 100 is disclosed and described withreference to FIGS. 1A-1D. As seen in FIG. 1A, the golf club head 100includes a face 110, a crown 120, a sole 130, a skirt 140, and a hosel150. Major portions of the golf club head 100 not including the face 110are considered to be the golf club body for the purposes of thisdisclosure. A coefficient of restitution feature (CORF) 300 is seen inthe sole 130 of the golf club head 100. In various embodiments, featuresof the golf club head 100 may include CORF 300 or may be found withoutCORF 300. In various embodiments, modifications to CORF 300 may beincluded and would be understood by one of skill in the art to beintended to be included within the scope of the current disclosure.

A three dimensional reference coordinate system 200 is shown. An origin205 of the coordinate system 200 is located at the geometric center ofthe face (CF) of the golf club head 100. See U.S.G.A. “Procedure forMeasuring the Flexibility of a Golf Clubhead,” Revision 2.0, Mar. 25,2005, for the methodology to measure the geometric center of thestriking face of a golf club. The coordinate system 200 includes az-axis 206, a y-axis 207, and an x-axis 208 (shown in FIG. 1B). Eachaxis 206,207,208 is orthogonal to each other axis 206,207,208. The golfclub head 100 includes a leading edge 170 and a trailing edge 180. Forthe purposes of this disclosure, the leading edge 170 is defined by acurve, the curve being defined by a series of forwardmost points, eachforwardmost point being defined as the point on the golf club head 100that is most forward as measured parallel to the y-axis 207 for anycross-section taken parallel to the plane formed by the y-axis 207 andthe z-axis 206. The face 110 may include grooves or score lines invarious embodiments. In various embodiments, the leading edge 170 mayalso be the edge at which the curvature of the particular section of thegolf club head departs substantially from the roll and bulge radii.

As seen with reference to FIG. 1B, the x-axis 208 is parallel to aground plane (GP) onto which the golf club head 100 may be properlysoled—arranged so that the sole 130 is in contact with the GP. They-axis 207 is also parallel to the GP and is orthogonal to the x-axis208. The z-axis 206 is orthogonal to the x-axis 208, the y-axis 207, andthe GP. The golf club head 100 includes a toe 185 and a heel 190. Thegolf club head 100 includes a shaft axis (SA) defined along an axis ofthe hosel 150. When assembled as a golf club, the golf club head 100 isconnected to a golf club shaft (not shown). Typically, the golf clubshaft is inserted into a shaft bore 245 defined in the hosel 150. Assuch, the arrangement of the SA with respect to the golf club head 100can define how the golf club head 100 is used. The SA is aligned at anangle 198 with respect to the GP. The angle 198 is known in the art asthe lie angle (LA) of the golf club head 100. A ground planeintersection point (GPIP) of the SA and the GP is shown for reference.In various embodiments, the GPIP may be used a point of reference fromwhich features of the golf club head 100 may be measured or referenced.As shown with reference to FIG. 1A, the SA is located away from theorigin 205 such that the SA does not directly intersect the origin orany of the axes 206,207,208 in the current embodiment. In variousembodiments, the SA may be arranged to intersect at least one axis206,207,208 and/or the origin 205. A z-axis ground plane intersectionpoint 212 can be seen as the point that the z-axis intersects the GP.

As seen with reference to FIG. 1C, the coefficient of restitutionfeature 300 (CORF) is shown defined in the sole 130 of the golf clubhead 100. A modular weight port 240 is shown defined in the sole 130 forplacement of removable weights. Various embodiments and systems ofremovable weights and their associated methods and apparatus aredescribed in greater detail with reference to U.S. Pat. No. 6,773,360,entitled “GOLF CLUB HEAD HAVING A REMOVABLE WEIGHT,” filed Nov. 8, 2002,and U.S. Pat. No. 7,166,040, entitled “REMOVABLE WEIGHT AND KIT FOR GOLFCLUB HEAD,” filed Feb. 23, 2004, which are incorporated by referenceherein in their entirety. The top view seen in FIG. 1D shows anotherview of the golf club head 100. The shaft bore 245 can be seen definedin the hosel 150. The cutting plane or cross section for FIG. 2 can alsobe seen in FIG. 1D. The cutting plane for FIG. 2 coincides with they-axis 207.

Referring back to FIG. 1A, a crown height 162 is shown and measured asthe height from the GP to the highest point of the crown 120 as measuredparallel to the z-axis 206. In the current embodiment, the crown height162 is about 36 mm. In various embodiments, the crown height 162 may be34-40 mm. In various embodiments, the crown height may be 32-44 mm. Invarious embodiments, the crown height may be 30-50 mm. The golf clubhead 100 also has an effective face height 163 that is a height of theface 110 as measured parallel to the z-axis 206. The effective faceheight 163 measures from a highest point on the face 110 to a lowestpoint on the face 110 proximate the leading edge 170. A transitionexists between the crown 120 and the face 110 such that the highestpoint on the face 110 may be slightly variant from one embodiment toanother. In the current embodiment, the highest point on the face 110and the lowest point on the face 110 are points at which the curvatureof the face 110 deviates substantially from a roll radius. In someembodiments, the deviation characterizing such point may be a 10% changein the radius of curvature. In the current embodiment, the effectiveface height 163 is about 27.5 mm. In various embodiments, the effectiveface height 163 may be 2-7 mm less than the crown height 162. In variousembodiments, the effective face height 163 may be 2-12 mm less than thecrown height 162. An effective face position height 164 is a height fromthe GP to the lowest point on the face 110 as measured in the directionof the z-axis 206. In the current embodiment, the effective faceposition height 164 is about 4 mm. In various embodiments, the effectiveface position height 164 may be 2-6 mm. In various embodiments, theeffect face position height 164 may be 0-10 mm. A length 177 of the golfclub head 177 as measured in the direction of the y-axis 207 is seen aswell with reference to FIG. 1A. In the current embodiment, the length177 is about 85 mm. In various embodiments, the length 177 may be 80-90mm. In various embodiments, the length 177 may be 73-97 mm. The distance177 is a measurement of the length from the leading edge 170 to thetrailing edge 180. The distance 177 may be dependent on the loft of thegolf club head in various embodiments. In one embodiment, the loft ofthe golf club head is about 15 degrees and the distance 177 is about91.6 mm. In one embodiment, the loft of the golf club head is about 18degrees and the distance 177 is about 87.4 mm. In one embodiment, theloft of the golf club head is about 21 degrees and the distance 177 isabout 86.8 mm.

The cutaway view of FIG. 2 shows the hollow nature of the golf club head100. The golf club head 100 of the current embodiment defines aninterior 320 that is bounded by the portions of the golf club head 100already discussed, including the face 110, crown 120, sole 130, andskirt 140, among other possible features that may provide a boundary tothe interior. In the current embodiment, the modular weight port 240provides access from any region exterior of the golf club head 100 tothe interior 320. In various embodiments, the weight port 240 may beomitted. One object among many of the current embodiment is to provideat least one of a low center of gravity and a forward center of gravitywhile maintaining a CORF 300. In various embodiments, low center ofgravity may be achieved without the inclusion of a CORF 300 and mayprovide at least one object of the current disclosure. In the currentembodiment, a second weight pad portion 345 provides a region ofincreased mass low inside the golf club head 100. Both a first weightpad portion 365 and the second weight pad portion 345 are portions of aweight pad 350 of the current embodiment. The weight pad 350 is integralwith the golf club head 100 in the current embodiment. In variousembodiments, the weight pad 350 may be of various materials and may bejoined to the golf club head 350. For example, in various embodiments,the weight pad 350 may be of tungsten, copper, lead, various alloys, andvarious other high density materials if a relocation of mass in thedirection of the weight pad 350 is desired. If the weight pad 350 is aseparate part joined to the golf club head 100, the weight pad 350 maybe joined to the golf club head 100 via welding, gluing, epoxy,mechanical fixing such as with fasteners or with key fit arrangements,or various other interface joining methods. In various embodiments, theweight pad 350 may be arranged on the inside or on the outside of thegolf club head 100. The first weight pad portion 365 extends a distance286 in the direction of the y-axis 207; the second weight pad portion345 extends a distance 288 in the direction of the y-axis 207; together,a length 290 defines the entirety of the weight pad 350 in the directionof the y-axis 207 and preferably is about 55 mm. In various embodiments,the length 290 may be 50-60 mm. In various embodiments, the length 290may be 45-62 mm. As seen, the weight pad 350 is offset from the leadingedge 170 a distance 361, as discussed in further detail below withreference to FIG. 3. In the current embodiment, the distance 361 is 5.3mm, and in various embodiments it may be desired for the distance 361 tobe as small as possible. In various embodiments, the distance 361 may be4.5-6.5 mm. The second weight pad portion 345 is of a thickness 347 asmeasured in the direction of the z-axis. In the current embodiment, thethickness 347 is about 3.6 mm. In various embodiments, the thickness 347may be 2-4 mm. In various embodiments, the thickness 347 may be up to 5mm. An end 273 of the weight pad 350 is seen in the cutaway view(further detail seen in FIG. 5). The end 273 is sloped for weightdistribution and manufacturability.

For reference, a center line 214 that is parallel to the z-axis 206 isshown at the center of the CORF 300 in the view of FIG. 2. The locationof the center line 214 is provided in greater detail below withreference to FIG. 3. A face-to-crown transition point 216 is also seenin the view. The face-to-crown transition point 216 is the point atwhich the face 110 stops and the crown 120 begins in a plane cut alongthe y-axis 207, which is at the origin 205 in the current embodiment or,globally, at CF. It is understood that the face 110 and crown 120transition along a curve, and the face-to-crown transition point 216 islocated only in the plane of the y-axis 207 in the current embodiment,or, globally, in a plane intersecting CF under any coordinate system.Because of roll radius and bulge radius of the face 110, theface-to-crown transition point 216 the transition between the face 110and crown 120 is no closer to the origin 205 in any geometric space thanat the face-to-crown transition point 216 in the current embodiment.Additionally, no part of the transition from face 110 to crown 120 iscloser to the z-axis 206 as measured parallel to the y-axis 207. As canbe seen in the view of FIG. 2, the center line 214 is closer to thez-axis 206 at all points as measured parallel to the y-axis 207 than theface-to-crown transition point 216. As such, no point of the transitionbetween the face 110 and crown 120 is closer to the z-axis 206 than acenter line passing through the center of the CORF 300 as measuredparallel to the y-axis 207, and, as such the CORF 300 is closer to theorigin 205 (CF) than the transition of the face 110 to the crown 120 atany point in the current embodiment. It should be noted that, as loft ofthe golf club head 100 reduces, the face-to-crown transition point 206may approach the center line 214—for example, in driver-type golf clubheads. However, the disclosure is accurate for the current embodimentand for all lofts of 13 degrees or greater.

Also seen in FIG. 2, a shaft plane z-axis 209 is seen. The shaft planez-axis 209 is parallel to z-axis 206 but is in the same plane as the SA.For reference the view of FIG. 6 shows the location of the shaft planez-axis 209 in the same cutting plane as the SA. The shaft plane z-axis209 is located a distance 241 from the z-axis 206 as measured in thedirection of the y-axis 207. In the current embodiment, the distance 241is 13.25 mm. In various embodiments, the distance 241 may be 13-14 mm.In various embodiments, the distance 241 may be 10-17 mm. In variousembodiments, the distance 241 may be as little as 1 mm and as large as24 mm. In the current embodiment, the shaft plane z-axis 209 is locatedcollinearly with a center of the modular weight port 240. The locationof the modular weight port 240 need not be correlated to the shaft planez-axis 209 for all embodiments.

With returning reference to FIG. 2, in the current embodiment, the CORF300 is defined in the sole 130 of the golf club head 100 such that theinterior 320 of the golf club head 100 is not physically bounded bymetal on all sides of the golf club head 100. In the current embodiment,the CORF 300 is a through-slot, thereby being defined as an open regionsuch that the interior 320 of the golf club head 100 is not separatedfrom the exterior at the CORF 300. The CORF 300 of the currentembodiment decouples the face 110 from the sole 130. Such a featureprovides multiple unexpected advantages, as will be described in greaterdetail with reference to application for U.S. patent bearing Ser. No.13/839,727, entitled “GOLF CLUB WITH COEFFICIENT OF RESTITUTIONFEATURE,” filed Mar. 15, 2013, which is incorporated by reference hereinin its entirety. In various embodiments, the various features of theCORF 300 may include various shapes, sizes, and various embodiments toachieve desired results. In multiple embodiments, the golf club head 100includes a face 110 that is fabricated separately and is secured to thegolf club head 100 after fabrication. In the current embodiment, theface 110 is secured to the golf club head 100 by welding. Weld beads 262a,b are seen in the current embodiment. A tangent face plane 235 (TFP)can be seen in the profile view as well. The TFP 235 is a plane tangentto the face 110 at the origin 205 (at CF). The TFP 235 approximates aplane for the face 110, even though the face 110 is curved at a rollradius and a bulge radius. The TFP 235 is angled at an angle 213 withrespect to the z-axis 206. The angle 213 in the current embodiment isthe same as a loft angle of the golf club head as would be understood byone of ordinary skill in the art. For the current embodiment, the SA isentirely within a plane parallel to the plane formed by the x-axis 208and the z-axis 206. In some embodiments, the SA will not be in a planeparallel to the plane formed by the x-axis 208 and the z-axis 206. Insuch embodiments, the shaft plane z-axis 209 will be a plane parallel tothe plane formed by the x-axis 208 and the z-axis 206 and intersectingthe GPIP.

A center of gravity 400 (CG) of the golf club head 100 is seen in FIG.2. Because the weight pad 350 makes up a large portion of the mass ofthe golf club head 100, the CG 400 is located relatively proximate theweight pad 350. The distance of the CG 400 from the GP as measured inthe direction of the z-axis 206 is seen and labeled as Δ_(z) in thecurrent view. In the current embodiment, Δ_(z) is about 12 mm. In atleast one embodiment, Δ_(z) is between 9 mm and 10 mm. In variousembodiments, Δ_(z) may be 11-13 mm. In various embodiments, Δ_(z) may be10-14 mm. In various embodiments, Δ_(z) may be 8-12 mm. In variousembodiments, Δ_(z) may be 8-16 mm. Similarly, a distance labeled as Δ₁is seen as the distance from the shaft plane z-axis 209 to the CG 400 asmeasured in the direction of the y-axis 207. In the current embodiment,Δ₁ is about 11.5 mm. In various embodiments, Δ₁ may be between andincluding 11 mm and 13 mm. In various embodiments, Δ₁ may be between andincluding 10 mm and 14 mm. In various embodiments, Δ₁ may be between andincluding 8 mm and 16 mm.

The location of the CG 400 and the actual measurements of Δ_(z) and Δ₁affect the playability of the golf club head 100. A projection 405 ofthe CG 400 can be seen orthogonal to the TFP 235. A projection point(not labeled in the current embodiment) is a point at which theprojection 405 intersects the TFP 235. In the current embodiment, thelocation of the CG 400 places the projection point at about the centerof the face 110, which is the location of the origin 205 (at CF) in thecurrent embodiment. In various embodiments, the projection point may bein a location other than the origin 205 (at CF).

The location of the CG 400—particularly the dimensions Δ_(z) andΔ₁—affect the use of the golf club head 100. Particularly with fairwaywood type golf club heads similar to the golf club head 100, small Δ_(z)has been used in various golf club head designs. Many designs haveattempted to maximize Δ₁ within the parameters of the particular golfclub head under design. Such a design may focus on MOI, as rearwardmovement of the CG can increase MOI in some designs.

However, there are several drawbacks to rearward CG location. One suchdrawback is dynamic lofting. Dynamic lofting occurs during the golfswing when the Δ₁ (for any club, Δ₁ is the distance from the shaft planeto the CG measured in the direction of the y-axis 207) is particularlylarge. Although the loft angle (seen in the current embodiment as angle213) is static, when the Δ₁ is large, the CG of the golf club head is inposition to cause the loft of the club head to increase during use. Thisoccurs because, at impact, the offset CG of the golf club head from theshaft axis creates a moment of the golf club head about the x-axis 208that causes rotation of the golf club head about the x-axis 208. Thelarger Δ₁ becomes, the greater the moment arm to generate moment aboutthe x-axis 208 becomes. Therefore, if Δ₁ is particularly large, greaterrotation is seen of the golf club head about the x-axis 208. Theincreased rotation leads to added loft at impact.

Dynamic lofting may be desired in some situations, and, as such, low andrearward CG may be a desired design element. However, dynamic loftingcauses some negative effects on the resulting ball flight. First, foreach degree of added dynamic loft, launch angle increases by 0.5-0.8°.Second, for each degree of added dynamic loft, spin rate increases byabout 200-250 rpm. The increased spin rate is due to several factors.First, the dynamic lofting simply creates higher loft, and higher loftleads to more backspin. However, the second and more unexpectedexplanation is gear effect. The projection of a rearward CG onto theface of the golf club head creates a projection point above center face(center face being the ideal impact location for most golf club heads).Gear effect theory states that, when the projection point is offset fromthe strike location, the gear effect causes rotation of the golf balltoward the projection point. Because center face is an ideal impactlocation for most golf club heads, offsetting the projection point fromthe center face can cause a gear effect on perfectly struck shots.Particularly with rearward CG fairway woods, loft of the golf club headcauses the projection point to be above the center face—or, above theideal strike location. This results in a tumbling motion of the headsuch that the gear effect increases backspin on center strikes,generating even greater backspin. Backspin may be problematic in somedesigns because the ball flight will “balloon”—or, in other words, risetoo quickly—and the distance of travel of the resultant golf shot willbe shorter than for optimal spin conditions. A third problem withdynamic lofting is that, in extreme cases, the trailing edge of the golfclub head may contact the ground, causing poor golf shots; similarly,the leading edge may raise off the ground, causing thin golf shots. Itshould be noted that the paragraph above assumes an ideal strikelocation of centerface. However, center face is not necessarily thepredicted or ideal strike location, and in various embodiments the CGprojection may be above center face but still below the intended strikelocation.

A further consideration with offsetting the CG such that the projectionpoint is not aligned with center face is the potential loss of energydue to spin. Because of the aforementioned gear effect problem, movingthe projection point anywhere other than the ideal strike locationreduces the energy transfer on ideal strikes, as more energy is turnedinto spin. As such, golf club heads for which the projection point isoffset from the ideal strike location may experience less distance on agiven shot than golf club heads for which the projection point isaligned with the ideal strike location (assumed to be at center face).

As stated previously, in some embodiments, the events described aboveare desired outcomes of the design process. In the current embodiment,the location of the CG 400 creates a projection point (not labeled) thatis closely aligned to the CF (at the origin 205).

As can be seen, the golf club head 100 of the current embodiment isdesigned to produce a small Δ_(z) and, thereby, to have a relatively lowCG 400. In various embodiments, however, the size of Δ₁ may become moreimportant to the goal to achieve ideal playing conditions for a givenset of design considerations.

A measurement of the location of the CG from the origin 205 (CF) alongthe y-axis 207—termed CG_(y) distance—is a sum of Δ₁ and the distance241 between the z-axis 206 and the shaft plane z-axis 209. In thecurrent embodiment of the golf club head 100, distance 241 is nominally13.25 mm, and Δ₁ is nominally 11.5 mm, although variations on the CG_(y)distance are described herein. In the current embodiment, the CG_(y)distance is 24.75 mm, although in various embodiments of the golf clubhead 100 the CG_(y) distance may be as little as 18 mm and as large as32 mm.

Knowing the CG_(y) distance allows the use of a CG effectiveness productto describe the location of the CG in relation to the golf club headspace. The CG effectiveness product is a measure of the effectiveness oflocating the CG low and forward in the golf club head. The CGeffectiveness product (CG_(eff)) is calculated with the followingformula and, in the current embodiment, is measured in units of thesquare of distance (mm²):

CG_(eff)=CG_(y)×Δ_(z)

With this formula, the smaller the CG_(eff), the more effective the clubhead is at relocating mass low and forward. This measurement adequatelydescribes the location of the CG within the golf club head withoutprojecting the CG onto the face. As such, it allows for the comparisonof golf club heads that may have different lofts, different faceheights, and different locations of the CF. For the current embodiment,CG_(y) is 24.75 mm and Δ_(z) is about 12 mm. As such, the CG_(eff) ofthe current embodiment is about 297 mm². In various embodiments,CG_(eff) is below 300 mm², as will be shown elsewhere in thisdisclosure. In various embodiments, CG_(eff) of the current embodimentsis below 310 mm². In various embodiments, CG_(eff) of the currentembodiments is below 315 mm². In various embodiments, CG_(eff) of thecurrent embodiments is below 325 mm².

Further, CG_(y) distance informs the distance of the CG to the face asmeasured orthogonally to the TFP 235. The distance to the CG measuredorthogonally to the TFP 235 is the distance of the projection 405. Forany loft θ of the golf club head (which is the same as angle 213 for thecurrent embodiment), the distance of the golf club face to the CG(D_(CG)) as measured orthogonally to the TFP 235 is described by theequation below:

D _(CG)=CG_(y)×cos(θ)

For the current embodiment, a loft of 15 degrees and CG_(y) of 24.75 mmmeans the D_(CG) is about 23.9 mm. In various embodiments, D_(CG) may be20-25 mm. In various embodiments, D_(CG) may be 15-30 mm. In variousembodiments, D_(CG) may be less than 35 mm. In various embodiments, Dmmay be governed by its relationship to previously determined CG_(y), Δ₁,Δ_(z), or some other physical aspect of the golf club head 100.

The CORF 300 of the current embodiment is defined proximate the leadingedge 170 of the golf club head 100, as seen with reference to FIG. 3. Aspreviously discussed, the CORF 300 of the current embodiment is athrough-slot providing a port from the exterior of the golf club head100 to the interior 320. The CORF 300 is defined on one side by a firstsole portion 355. The first sole portion 355 extends from a regionproximate the face 110 to the sole 130 at an angle 357, which is acutein the current embodiment. In various embodiments, the first soleportion 355 is coplanar with the sole 130; however, it is not coplanarin the current embodiment. In the current embodiment, the angle 357 isabout 88 degrees. In various embodiments, the angle 357 may be 85-90degrees. In various embodiments, the angle 357 may be 82-92 degrees. Thefirst sole portion 355 extends from the face 110 a distance 359 of about5.6 mm as measured orthogonal to the TFP 235. In various embodiments,the distance 359 may be 5-6 mm. In various embodiments, the distance 359may be 4-7 mm. In various embodiments, the distance 359 may be up to12.5 mm. The first sole portion 355 projects along the y-axis 207 thedistance 361 as measured to the leading edge 170, which is the samedistance that the weight pad 350 is offset from the leading edge 170. Inthe current embodiment, the distance 361 is about 5 mm. In variousembodiments, the distance 361 is 4.5-5.5 mm. In various embodiments, thedistance 361 is 3-7 mm. In various embodiments, the distance 361 may beup to 10 mm. In the current embodiment, the distances 359,361 aremeasured at the cutting plane, which is coincident with the y-axis 207and z-axis 206. In various embodiments, measurements—including anglesand distances such as distances 359,361—may vary depending on thelocation where measured and as based upon the shape of the CORF 300.

The CORF 300 is defined over a distance 370 from the first sole portion355 to the first weight pad portion 365 as measured along the y-axis. Inthe current embodiment, the distance 370 is about 3.0 mm. In variousembodiments, the distance 370 may be larger or smaller. In variousembodiments, the distance 370 may be 2.0-5.0 mm. In various embodiments,the distance 370 may be variable along the CORF 300. It would beunderstood by one of skill in the art that, in various embodiments, thefirst sole portion 355 may extend in a location for which no rearwardvertical surface 385 b is immediately adjacent and, as such, thedistance 370 may become large if measured along the y-axis 207. Aspreviously discussed, the center line 214 passes through the center ofthe CORF 300. The center of the CORF 300 is defined by a distance 366,which is exactly one half the distance 370. In the current embodiment,the distance 366 is 1.5 mm.

The CORF 300 is defined distal the leading edge 170 by the first weightpad portion 365. The first weight pad portion 365 in the currentembodiment includes various features to address the CORF 300 as well asthe modular weight port 240 defined in the first weight pad portion 365.In various embodiments, the first weight pad portion 365 may be variousshapes and sizes depending upon the specific results desired. In thecurrent embodiment, the first weight pad portion 365 includes anoverhang portion 367 over the CORF 300 along the y-axis 207. Theoverhang portion 367 includes any portion of the weight pad 350 thatoverhangs the CORF 300. For the entirety of the disclosure, overhangportions include any portion of weight pads overhanging the CORFs of thecurrent disclosure. The overhang portion 367 includes a faceward mostpoint 381 that is the point of the overhang portion 367 furthest towardthe leading edge 170 as measured in the direction of the y-axis 207.

The overhang portion 367 overhangs a distance that is about the same asthe distance 370 of the CORF 300 in the current embodiment. In thecurrent embodiment, the weight pad 350 (including the first weight padportion 365 and the second weight pad portion 345) are designed toprovide the lowest possible center of gravity of the golf club head 100.A thickness 372 of the overhang portion 367 is shown as measured in thedirection of the z-axis 206. The thickness 372 may determine how mass isdistributed throughout the golf club head 100 to achieve desired centerof gravity location. The overhang portion 367 includes a sloped end 374that is about parallel to the face 110 (or, more appropriately, to theTFP 235, not shown in the current view) in the current embodiment,although the sloped end 374 need not be parallel to the face 110 in allembodiments. A separation distance 376 is shown as the distance betweenan inner surface 112 of the face 110 and the sloped end 374 as measuredorthogonally to the TFP 235. In the current embodiment, the separationdistance 376 of about 4.5 mm is seen as the distance between the innersurface 112 of the face 110 and the sloped end 374 of the overhangportion 367 as measured orthogonal to the TFP 235. In variousembodiments, the separation distance 376 may be 4-5 mm. In variousembodiments, the separation distance 376 may be 3-6 mm. The CORF 300includes a beveled edge 375 (shown as 375 a and 375 b in the currentview). In the current embodiment, the beveled edge 375 provides somestress reduction function, as will be described in more detail later. Invarious embodiments, the distance that the overhang portion 367overhangs the CORF 300 may be smaller or larger, depending upon thedesired characteristics of the design.

As can be seen, an inside surface 382 of the first sole portion 355extends downward toward the sole 130. The inside surface 382 terminatesat a low point 384. The CORF 300 includes a vertical surface 385 (shownas 385 a,b in the current view) that defines the edges of the CORF 300.The CORF 300 also includes a termination surface 390 that is definedalong a lower surface of the overhang portion 367. The terminationsurface 390 is offset a distance 392 from the low point 384 of theinside surface 382. The offset distance 392 provides clearance formovement of the first sole portion 355, which may deform in use, therebyreducing the distance 370 of the CORF 300. Because of the offsetdistance 392, the vertical surface 385 is not the same for verticalsurface 385 a and vertical surface 385 b. However, the vertical surface385 is continuous around the CORF 300. In the current embodiment, theoffset distance 392 is about 0.9 mm. In various embodiments, the offsetdistance 392 may be 0.2-2.0 mm. In various embodiments, the offsetdistance 392 may be up to 4 mm. An offset to ground distance 393 is alsoseen as the distance between the low point 384 and the GP. The offset toground distance 393 is about 2.25 mm in the current embodiment. Theoffset to ground distance 393 may be 2-3 mm in various embodiments. Theoffset to ground distance 393 may be up to 5 mm in various embodiments.A rearward vertical surface height 394 describes the height of thevertical surface 385 b and a forward vertical surface height 396describes the height of the vertical surface 385 a. In the currentembodiment, the forward vertical surface height 396 is about 0.9 mm andthe rearward vertical surface height 394 is about 2.2 mm. In variousembodiments, the forward vertical surface height 396 may be 0.5-2.0 mm.In various embodiments, the rearward vertical surface height 394 may be1.5-3.5 mm. A termination surface to ground distance 397 is also seenand is about 3.2 mm in the current embodiment. The termination surfaceto ground distance 397 may be 2.0-5.0 mm in various embodiments. Thetermination surface to ground distance 397 may be up to 10 mm in variousembodiments.

In various embodiments, the vertical surface 385 b may transition intothe termination surface 390 via fillet, radius, bevel, or othertransition. One of skill in the art would understand that, in variousembodiments, sharp corners may not be easy to manufacture. In variousembodiments, advantages may be seen from transitions between thevertical surface 385 b and the termination surface 390. Relationshipsbetween these surfaces (385, 390) are intended to encompass these ideasin addition to the current embodiments, and one of skill in the artwould understand that features such as fillets, radii, bevels, and othertransitions may substantially satisfy such relationships. For the sakeof simplicity, relationships between such surfaces shall be treated asif such features did not exist, and measurements taken for the sake ofrelationships need not include a surface that is fully vertical orhorizontal in any given embodiment.

The thickness 372 of the overhang portion 567 of the current embodimentcan be seen. The thickness 372 in the current embodiment is about 3.4mm. In various embodiments, the thickness 372 may be 3-5 mm. In variousembodiments, the thickness 372 may be 2-10 mm. As shown with relation toother embodiments of the current disclosure, the thickness 372 maybegreater if combined with features of those embodiments. Additionally,the rearward vertical surface height 394 defines the distance of theCORF 300 from the termination of the bevel 375 to the terminationsurface 390 as well as the distance of the vertical surface 385 b,although such a relationship is not necessary in all embodiments. As canbe seen, each of the offset distance 392, the offset to ground distance393, and the vertical surface height 394 is less than the thickness 372.As such, a ratio of each of the offset distance 392, the offset toground distance 393, and the vertical surface height 394 to thethickness 372 is less than or equal to 1. In various embodiments, theCORF 300 may be characterized in terms of the termination surface toground distance 397. For the current embodiment, a ratio of thetermination surface to ground distance 397 as compared to the thickness372 is about 1, although it may be less in various embodiments. For thesake of this disclosure, the ratio of termination surface to grounddistance 397 as compared to the thickness 372 is termed the “CORF massdensity ratio.” While the CORF mass density ratio provides one potentialcharacterization of the CORF, it should be noted that all ratios citedin this paragraph and throughout this disclosure with relation todimensions of the various weight pads and CORFs may be utilized tocharacterize various aspects of the CORFs, including mass density,physical location of features, and potential manufacturability. Inparticular, the CORF mass density ratio and other ratios herein at leastprovide a method of describing the effectiveness of relocating mass tothe area of the CORF, among other benefits.

The CORF 300 may also be characterized in terms of distance 370. A ratioof the offset distance 392 as compared to the distance 370 is aboutequal to 1 in the current embodiment and may be less than 1 in variousembodiments.

In various embodiments, the CORF 300 may be plugged with a pluggingmaterial (not shown). Because the CORF 300 of the current embodiment isa through-slot (providing a void in the golf club body), it isadvantageous to fill the CORF 300 with a plugging material to preventintroduction of debris into the CORF 300 and to provide separationbetween the interior 320 and the exterior of the golf club head 100.Additionally, the plugging material may be chosen to reduce or eliminateunwanted vibrations, sounds, or other negative effects that may beassociated with a through-slot. The plugging material may be variousmaterials in various embodiments depending upon the desired performance.In the current embodiment, the plugging material is polyurethane,although various relatively low modulus materials may be used, includingelastomeric rubber, polymer, various rubbers, foams, and fillers. Theplugging material should not substantially prevent deformation of thegolf club head 100 when in use (as will be discussed in more detaillater).

The CORF 300 is shown in the view of FIG. 4. The CORF 300 of the currentembodiment includes multiple portions that define its shape. The CORF300 includes a central portion 422 that preferably extends most of thelength of the CORF 300. The central portion 422 is relatively straightas compared to other portions of the CORF 300. In the currentembodiment, the central portion 422 is a curve of a radius of about 100mm. A profile of the central portion 422 approximately follows theprofile of the leading edge 170 such that the curvature of the centralportion 422 does not substantially deviate from a curvature of theleading edge 170. The distance 370 can be seen as the defining width ofthe CORF 300. The defining width is measured orthogonally to thevertical surface 385 such that the defining width is not necessarily ata constant angle with respect to any axis (x-axis 208, y-axis 207,z-axis 206). The CORF 300 includes two additional portions. A heelwardreturn portion 424 and a toeward return portion 426 are seen. Theheelward return portion 424 and toeward return portion 426 diverge fromthe leading edge 170 such that a curvature of the CORF 300 in the regionof the heelward return portion 424 and the toeward return portion 426 isnot substantially the same as the curvature of the leading edge 170. Inthe current embodiment, the defining width of the CORF 300 remainsconstant such that the distance 370 defines the defining width of theCORF 300 throughout all portions (central portion 422, heelward returnportion 424, toeward return portion 426). In various embodiments, thedefining width of at least one of the heelward return portion 424 andthe toeward return portion 426 may be variable with respect to thedefining with of the central portion 422. In the current embodiment, thedivergence of the heelward return portion 424 and the toeward returnportion 426 from the leading edge 170 provides additional stressreduction to avoid potential failure—such as cracking or permanentdeformation—of the golf club head 100 along the CORF 300. In the currentembodiment, the heelward return portion 424, central portion 422, andtoeward return portion 426 are not constant radius between the threeportions. Instead, the CORF 300 of the current embodiment is a multipleradius (hereinafter “MR”) CORF 300. Because of the arrangement of theview of FIG. 4, the termination surface 390 can be seen under the CORF300.

The CORF 300 includes a heelward end 434 and a toeward end 436. Each end434,436 of the CORF 300 is identified at the end of the beveled edge375. In various embodiments, the beveled edge 375 may be omitted, andthe ends 434,436 may be closer together as a result. A distance 452 isshown between the toeward end 436 and the heelward end 434 as measuredin the direction of the x-axis 208. In the current embodiment, thedistance 452 is 40-43 mm. In various embodiments, the distance 452 maybe 33-50 mm. In various embodiments, the distance 452 may be larger orsmaller than the ranges cited herein and is limited only by the size ofthe golf club head. The CORF 300 includes a distance 454 as measured inthe direction of the y-axis 207. In the current embodiment, the distance454 is 9-10 mm. In various embodiments, the distance 454 may be 7-12 mm.In various embodiments, the distance 454 may be larger or smaller thanranges cited herein and is limited only by the size of the golf clubhead.

As indicated previously, the disclosure of application for U.S. patentbearing Ser. No. 13/839,727, entitled “GOLF CLUB WITH COEFFICIENT OFRESTITUTION FEATURE,” filed Mar. 15, 2013, is incorporated by referenceherein in its entirety. The remaining embodiments of application forU.S. patent bearing Ser. No. 13/839,727 have been omitted forefficiency. However, the entire disclosure of application for U.S.patent bearing Ser. No. 13/839,727 should be considered includedherewith as if reproduced within the body of this disclosure.

As can be understood with reference to application for U.S. patentbearing Ser. No. 13/839,727, the inclusion of a CORF such as CORF 300leads to increased flexibility of the golf club face 110, particularlyon low face shots. One of skill in the art would understand that such alow face flexibility can increase COR for the entire golf club face 110,leading to higher energy transfer on any shot. Additionally, featuresdescribed in the application for U.S. patent bearing Ser. No. 13/839,727provide for low and/or forward CG location, explaining the spin-loweringeffect of such arrangement of mass.

However, what is less understood by review of the application for U.S.patent bearing Ser. No. 13/839,727 is the effect of the CORF 300 andsimilar features on resultant spin, nor was it well understood howmodifications to various CORF features would affect spin. Features ofthe current disclosure discuss, among other items, the effect of variousmodifications on the golf club head to alter spin.

In short, it has been surprisingly discovered that boundary conditionsof the face of a golf club head dramatically influence spin profiles inaddition to COR. As such, COR features (CORFs) are more appropriatelytermed “boundary condition features,” or BCFs, because the presence ofsuch features alters spin in addition to COR and, perhaps, otherfeatures. BCFs of the current disclosure may include elements to softenthe boundary condition along the face in various embodiments. BCFs ofthe current disclosure may include elements to stiffen the boundarycondition along the face in various embodiments. One of skill in the artwould understand that the CORFs of the application for U.S. patentbearing Ser. No. 13/839,727 are but a few exemplary embodiments ofsoftening BCFs. Both softening BCFs and stiffening BCFs will bedescribed in greater detail herein.

As generally understood by one of skill in the art, the boundary of anygolf club face can be represented as the location that the face of thegolf club head meets portions of the golf club body. Given the speed andintensity of impact of the golf club face with a golf ball, theboundaries may be relatively rigid as compared with the center of thegolf club face, where the face may be thinner than the edges wherereinforcement occurs. The relative flexibility of a particular boundaryof the face is referred to herein as the “boundary condition.”

As noted, the manipulation of the boundary condition of the face of thegolf club head can result in altered spin profiles given the sameconditions of impact of the golf club head. In the most simple form, therigidity of any boundary of the face can alter the resulting golf shot.As previously noted, it became advantageous to increase COR in certaingolf club heads by freeing the boundary condition with CORFs such asCORF 300. However, such a CORF does not appear to have a material impacton the resultant shot if the boundary condition of the opposite side ofthe face is symmetrical—or, the same relative flexibility as theboundary condition proximate the CORF.

To increase COR low on the face, golf club heads of the disclosure ofapplication for U.S. patent bearing Ser. No. 13/839,727 included aboundary softening feature—namely, CORFs such as CORF 300. Such featuresprovided a reduction in the rigidity of the leading edge of the golfclub heads of that disclosure, leading to increased flexibility low onthe face. However, it was not understood at the time that rigidity ofthe top of the golf club face also had an impact on the resultant shot.Were a CORF to be included in the crown of the golf club head—forexample, as described in application for U.S. patent bearing Ser. No.12/791,025, entitled “HOLLOW GOLF CLUB HEAD,” filed Jun. 1, 2010—thecrown region would be relatively less rigid than previously. Theresulting effect would be that the face would flex similarly to itsbehavior without CORFs because both the crown boundary condition and thesole boundary condition of the face would be about the sameflexibility—or, in other words, symmetrical. With a symmetrical boundarycondition, the resulting impact is similar, regardless of whether theboundary condition is rigid or relatively more flexible.

When a golf club head includes one boundary condition as relativelyrigid and another boundary condition as relatively less rigid or moreductile, the resulting boundary condition is termed “asymmetrical.” Anasymmetrical boundary condition alters shot performance dramatically ascompared to the symmetrical boundary condition. CORFs that result inasymmetrical boundary conditions provide greater impact on COR thanCORFs that result in symmetrical boundary conditions. Further, creatingan asymmetrical boundary condition has a material impact on golf ballspin characteristics, while creating a symmetrical boundary conditionhas almost no impact on golf ball spin characteristics as compared to agolf club head without a modified boundary condition.

In general, when one side of the boundary is rigid and one side isrelatively ductile (asymmetrical boundary condition), it has beensurprisingly discovered that the resulting spin profile will be alteredin a direction consistent with the relatively more ductile boundary. Forexample, if the boundary condition of the face proximate the crown (the“crown boundary condition” or “CBC”) is generally more rigid than theboundary condition of the face proximate the sole (the “sole boundarycondition” or “SBC”), then, upon impact with a golf ball, the ball willtend to spin in a direction toward the sole, thereby reducing backspinon the golf shot. If the CBC is more flexible than the SBC, then, uponimpact with a golf ball, the ball will tend to spin in a directiontoward the crown, thereby increasing backspin on the golf shot.

With this unexpected discovery comes the ability to manipulate the spincharacteristics of various golf club heads. For example, it is generallydesirable in driver-type golf club heads to provide a golf club headwith as low spin as possible. Similarly, in some clubs used to approacha green (for example, hybrid type golf club heads), it may be desirableto reduce spin in some scenarios—which will generally increasedistance—or to increase spin in other scenarios—which will allow forgreater ability to hold greens on long approach shots. Many features ofthe current disclosure will be particularly described with reference tofeatures of the sole of the golf club head. However, in variousembodiments, features seen on the sole may be modified or relocated toprovide similar interactions on the crown of the various golf clubheads. One of skill in the art would understand that the descriptionsprovided herein are not intended to rely on placement in one locationunless described in a manner commensurate with that location only, aswould be understood by one of skill in the art.

As seen with reference to FIG. 5, a golf club head 1100 includesfeatures and components generally similar to those of golf club head100. The sole 130 of the golf club head 1100 includes a BCF 1300. TheBCF 1300 of the current embodiment is a softening BCF, as describedpreviously in this disclosure.

The BCF 1300 of the current embodiment includes multiple portions thatdefine its shape. The BCF 1300 includes a central portion 1422 thatcomprises a plurality of the BCF 1300. In the current embodiment, thecentral portion 1422 includes a curved shape. In contrast to somefeatures of various embodiments discussed herein, the BCF 1300 includesa curvature that is opposite of the curvature of the leading edge 170.As such, a central point 1423 of a forwardmost edge 1425 of the BCF 1300is further from the leading edge 170 than a first central portion endpoint 1433 or a second central portion end point 1435. In the currentembodiment, central point 1423 is removed from the leading edge 170 toreduce stress concentration, which can cause weakening or failure of thegolf club head. The BCF 1300 includes two additional portions. Aheelward return portion 1424 and a toeward return portion 1426 are seen.The heelward return portion 1424 and toeward return portion 1426 divergefrom the leading edge 170. In the current embodiment, the defining widthof the BCF 1300 remains about constant, as the curvature of arearwardmost edge 1439 generally follows the curvature of theforwardmost edge 1425. In various embodiments, the defining width of atleast one of the heelward return portion 1424 and the toeward returnportion 1426 may be variable with respect to the defining with of thecentral portion 1422. In the current embodiment, the divergence of theheelward return portion 1424 and the toeward return portion 1426 fromthe leading edge 170 provides additional stress reduction to avoidpotential failure—such as cracking or permanent deformation—of the golfclub head 1100 along the BCF 1300. In the current embodiment, theheelward return portion 1424, central portion 1422, and toeward returnportion 1426 are not constant radius between the three portions.Instead, the BCF 1300 of the current embodiment is a multiple radius(hereinafter “MR”) BCF 1300.

The BCF 1300 includes a heelward end 1434 and a toeward end 1436. Adistance 1452 is shown between the toeward end 1436 and the heelward end1434 as measured in the direction of the x-axis 208. In the currentembodiment, the distance 1452 is about 83 mm. In various embodiments,the distance 1452 may be 80-85 mm. In various embodiments, the distance1452 may be 75-95 mm. In various embodiments, the distance 1452 may belarger or smaller than the ranges cited herein and is limited only bythe size of the golf club head. The BCF 1300 includes a distance 1454 asmeasured in the direction of the y-axis 207. In the current embodiment,the distance 1454 is 10-14 mm. In various embodiments, the distance 1454may be 7-20 mm. In various embodiments, the distance 1454 may be largeror smaller than ranges cited herein and is limited only by the size ofthe golf club head. In various embodiments, the distance 1452 is between70% and 95% of the heel-to-toe length of the golf club head 1100, whichis a length from the toe 185 to the heel 190. In various embodiments,the distance 1452 is 80% to 90% of the heel-to-toe length of the golfclub head. In various embodiments, the distance 1452 may be compared asa percentage of the length 177.

As can be seen with reference to FIGS. 5, 6B, portions of the BCF 1300extend onto the skirt 140 of the golf club head 1100 proximate the toe185 and the heel 190. The size of the BCF 1300 is much larger than thesize of the CORF 300 and various CORFs disclosed in application for U.S.patent bearing Ser. No. 13/839,727.

With specific reference to FIG. 6A, the BCF 1300 extends to a height1472 above the GP that is about 8.5 mm. In various embodiments, the BCF1300 may extend between 8-9 mm. In various embodiments, the BCF 1300 mayextend 6-11 mm. In various embodiments, the BCF 1300 may extend 4.5-11.5mm. The BCF 1300 extends into the skirt 140 of the golf club head 1100.

As seen with reference to FIG. 7, a weight pad 1350 is included with thegolf club head 1100 as similar to prior embodiments and those disclosedin application for U.S. patent bearing Ser. No. 13/839,727. The weightpad 1350 includes an inclined surface 1273 providing generallyincreasing thickness from a rearwardmost end 1274 to a forwardmost end1276 of the weight pad 1350. A thickness 1278 of the mass pad 1350 ismeasured parallel to the z-axis 206 at the forwardmost end 1276. In thecurrent embodiment, the thickness 1278 is about 10.3 mm. In variousembodiments the thickness 1278 may range from 9 to 12 mm. In variousembodiments, the thickness 1278 may range from 6 to 15 mm. It should benoted that features of the weight pad 1350 proximate the face 110 mayprovide for decreased thickness in various locations. A center ofgravity 1400 is seen in the view. The center of gravity 1400 provides aprojection point 1510 that is below the CF 205. In the currentembodiment, the projection point 1510 is about 0.1 mm below CF 205. Invarious embodiments, various mass placement may result in projectionpoints such as projection point 1510 being below the CF 205 by 0.5 mm,by 1.0 mm, by 1.5 mm, by 2.0 mm, and by about 4 mm below CF 205 invarious embodiments. In various embodiments, the projection point 1510may be up to 7 mm below CF 205. In various embodiments, the projectionpoint 1510 may be above center face by up to 2 mm while still below theintended strike location. Additionally, projection points may be asdiscussed with respect to various other embodiments of the currentdisclosure and with respect to the various embodiments of applicationfor U.S. patent bearing Ser. No. 13/839,727. Distances for Δ_(z) and Δ₁in the current embodiment are 12.1 mm and 9.4 mm, respectively. Invarious embodiments, distances for Δ_(z) may be 11-13 mm, 10-13.5 mm,and 8-11.5 mm. In various embodiments, distances for Δ_(z) may be aslittle as 6 mm and as great as 18 mm. In various embodiments, Δ₁ may be9-10 mm, 8-11 mm, 7-11.5 mm, and 6.5-13 mm. In various embodiments, Δ₁may be as little as 2 mm. All ranges cited in the current disclosure areintended to be inclusive except where indicated otherwise. Ranges forΔ_(z) and Δ₁ may also be as discussed with respect to various otherembodiments of the current disclosure and with respect to the variousembodiments of application for U.S. patent bearing Ser. No. 13/839,727.

In the current embodiment, an absolute width 1370 of the BCF 1300 isprovided. In the current embodiment, the absolute width 1370 is about5.5 mm. In various embodiments, the absolute width 1370 may be between 4mm to 7 mm. In various embodiments, the absolute width 1370 may be up to10 mm. Prior embodiments provide other limits for the width 1370 ofvarious types of BCFs and CORFs such that one of skill in the art wouldunderstand that different sized BCFs may be created in accord with thecurrent disclosure. In the current embodiment, the absolute width 1370is measured orthogonally to the vertical surfaces 385 a,b, which, in thecurrent embodiment, are not parallel to the SA or the z-axis 206.However, in the current embodiment, the distance of the BCF as measuredparallel to the y-axis is about the same as the absolute distance. Forranges as to distances provided as absolute distances in the currentdisclosure, one of skill in the art would understand that measurementsas attained in a particular coordinate system would not be substantiallydifferent if the angle of measurement is not a great angle with respectto the coordinate system. As such, in the current instance, the absolutewidth 1370 is about the same as a width as measured parallel to they-axis. The BCF 1300 includes a radius 1402 connecting the sole 130 tothe rearward vertical surface 385 b. The radius 1402 may provide betterturf interaction on shots wherein a filler material may not cover such atransition region between the rearward vertical surface 385 b and thesole 130.

In the current embodiment, the first sole portion 355 includes a lipfeature 1555. The lip feature 1555 provides a physical extension of thevertical surface 385 a above what would be possible merely from thethickness of the first sole portion 355. As such, the lip feature 1555is a thickened portion, and includes a thickness greater than the firstsole portion 355. A fillet 1557 is included between the first soleportion 355 and the lip feature 1555. The lip feature 1555 of thecurrent embodiment terminates without connecting to other features ofthe golf club head 1100, although various embodiments may includevarious connection features.

As can be seen, the first sole portion 355 is of a moderate thickness.As previously noted (with specific reference to FIG. 5), the distance1452 of the BCF 1300 is much larger than disclosed in prior embodiments.As such, portions of the BCF 1300 can experience much larger flexing andmuch higher concentration of stress. The inclusion of the lip feature1555 provides reinforcement of increased material thickness at thelocation of most stress concentrations, which would tend to locate alongthe walls of the BCF 1300. Such features can reinforce the BCF 1300against cracking or other failure without increasing the thickness ofthe first sole portion 355, thereby maintaining much of the flexibilityof the BCF 1300 to allow greater flexure of the face 110 of the golfclub head.

With reference to FIG. 8, distances 359 and 361 are seen, with distance359 measured orthogonal to the TFP 235 and distance 361 measuredparallel to the y-axis 207. In the current embodiment, both distances359 and 361 are between 9 mm and 9.5 mm. In various embodiments, thedistances 359 and 361 may be substantially different from each other ormay be substantially the same depending on the angle 357 of the firstsole portion 355. In various embodiments, the distances 359, 361 may bebetween 7 mm and 11 mm. In various embodiments, the distances 359,361may be up to 15 mm. In the current embodiment, the first sole portion355 is of an absolute thickness 1411 of about 1.80 mm. In variousembodiments, the first sole portion 355 may be 1 mm to 2 mm in thickness1411. In various embodiments, the first sole portion 355 may be aslittle as 0.5 mm, and in various embodiments the first sole portion 355may be up to 4 mm in thickness 1411. In various embodiments, the firstsole portion 355 may be of various thicknesses along its profile in thedirections of the x-axis 208, the y-axis 207, and the z-axis 206. Invarious embodiments, the first sole portion 355 may be of constantlyvarying profile or of consistently varying profiles. One of skill in theart would understand that modifications in view of other embodiments ofthe current disclosure and of the disclosure of application for U.S.patent bearing Ser. No. 13/839,727 may be implemented without departingsubstantially from the general scope of the disclosure.

The lip feature 1555 extends into the golf club head 1100 by a distance1393 of about 6 mm in the current embodiment. The distance 1393 is anabsolute distance, although the distance as measured parallel to the TFP235 or the z-axis 206 would not be substantially different in thecurrent embodiment. In various embodiments, the lip feature 1555 may bebetween 4 mm and 8 mm. In various embodiments, the lip feature 1555 maybe as little as 2 mm and as large as 15 mm. A thickness 1558 of the lipfeature 1555 is about 1.0 mm. In various embodiments, the thickness 1558may be as little as 0.5 mm and as large as 4 mm. A termination surface1390 of an overhang portion 1367 is located a distance 1397 above the GPof about 8 mm in the current embodiment. In various embodiments, thedistance 1397 may be 4 mm to 18 mm. In various embodiments, the distance1397 may be 6 mm to 12 mm. In various embodiments, the terminationsurface 390 may be omitted, and in various embodiments the overhangportion 1367 may be omitted in its entirety or may be enlarged.

As seen with reference to FIG. 9, portions of the overhang portion 1367are coincident with the weight pad 1350. However, proximate the heelwardend 1434 and the toeward end 1436, the overhang portion 1367 divergesfrom the weight pad 1350. As can be seen, in the current embodiment,matter has been added in proximate the heelward end 1434 and the toewardend 1436 to reinforce the BCF 1300 against mechanical failure. Aheelward reinforced region 1903 and a toeward reinforced region 1907 areareas of increased thickness of material in the current embodiment. Inthe current embodiment, a rib 1901 connects the BCF 1300 with the skirt140 proximate the toe 185. Such a feature may be included for mechanicalreinforcement and/or for sound performance.

As seen with reference to FIG. 10, a BCF 2300 may be implemented into agolf club head 2100 that is a driver-type head in the currentembodiment. The size of the BCF 2300 implemented into golf club head2100 is about the same as the BCF 1300 for the golf club head 1100,although various features may change by the implementation of the BCF2300 into the driver type golf club head 2100.

With specific reference to FIG. 11A, the BCF 2300 extends to a height2472 above the GP that is about 14.0 mm. In various embodiments, theheight 2472 is about 12-16 mm. In various embodiments, the height 2472is 10-20 mm. In various embodiments, the height 2472 is greater than 11mm. The BCF 2300 is extends into the skirt 140 of the golf club head2100. The BCF 2300 may have somewhat different dimensions than BCF 1300or may be substantially the same as BCF 1300 in various embodiments. Ascan be seen with reference to FIGS. 11B-11C, the length 177 of the golfclub head 2100 in the current embodiment is about 116 mm. In variousembodiments, the length 177 of the golf club head 2100 may be 110-120mm. In various embodiments, the length 177 may be 105-125 mm. In variousembodiments, the length 177 of the golf club head 2100 may be greaterthan 100 mm. The golf club head 2100 includes a heel-toe length 2177 ofabout 120 mm. In various embodiments, the heel-toe length 2177 may be110 mm to 130 mm. In various embodiments, the heel-toe length 2177 maybe greater than 100 mm. The golf club head 2100 includes a crown height162 of about 64 mm. In various embodiments, the crown height 162 may be60-70 mm. In various embodiments, the crown height may be greater than55 mm.

The golf club head 2100 is seen in greater detail with reference to FIG.12. The golf club head 2100 includes weight pad 2350. A heelwardreinforced region 2903 and a toeward reinforced region 2907 are areas ofincreased thickness of material in the current embodiment. Eachreinforced region 2903,2907 includes a plurality of ribs 2901 a,b,c,d toaid in durability and sound performance. The BCF 2300 of the currentembodiment includes an overhang portion 2367 that is similar in shapeand function as the overhang portion 1367. However, in the currentembodiment, the overhang portion 2367 includes a rib 2368 extending froma top of the overhang portion 2367 into the hollow space of the golfclub body. Various additional ribs are seen connecting the skirt andsole of the golf club head 2100 for additional sound performance.

The view of FIG. 13 includes a second view of the rib 2368 to show thelocation in the golf club head. As can be seen, the rib 2368 isgenerally triangular and has its upwardmost extent of the projection ata location about consistent with the CF 205—or, in other words,intersecting the plane formed by the y-axis 207 and the z-axis 206—withthe rib 2368 tapering along its length toward both the heel 190 and thetoe 185. The rib 2368 provides improved sound performance.

Also seen in the view of FIG. 13 is a second BCF 2800 located proximateto the crown 120 of the golf club head 2100. The BCF 2800 is astiffening BCF in the current embodiment. The BCF 2800 is a plurality ofribs located centrally to the golf club head proximate the face-to-crowntransition point 216. The BCF 2800 has a length 2803 of about 14 mm inthe current embodiment. In various embodiments, the length 2803 may belarger or smaller as needed to tune the stiffness of the BCF 2800 andthe portion of the face 110 proximate the crown 120. As one of skill inthe art would understand, a smaller length 2803 of BCF 2800 willgenerally be less stiff than a larger length 2803 when all materials,angles, joints, and various thicknesses are the same. In variousembodiments, the length 2803 may be 12-16 mm. In various embodiments,the length 2803 may be 10-20 mm. In various embodiments, the length 2803may be greater than 5 mm.

As seen with reference to FIG. 14, the BCF 2800 includes three ribs 2805a,b,c. In various embodiments, any number of ribs 2805 may be utilized.In various embodiments, ribs may be of different sizes and shapes. Eachrib 2805 a,b,c is separated from the next rib 2805 a,b,c by a distance2815 a,b. Each distance 2815 a,b, is about 12 mm in the currentembodiment. In various embodiments, the distances 2815 a,b may begreater or smaller depending on the goal of the design to stiffen orsoften the BCF 2800. Each rib 2805 is of a thickness 2806 a,b,c (2806a,b omitted for ease of view). In the current embodiment, the thickness2806 is about 1 mm, although in various embodiments the thickness may be0.25 mm to 4 mm in various embodiments. In various embodiments,stiffening BCFs may include thickened regions, multi-materialimplementations, various bosses or other features as may be understoodby one of skill in the art.

A golf club head 3100 includes a BCF 3300 as shown with reference toFIG. 15. The BCF 3300 is similar in general shape to the CORF 300 (alsoa BCF) disclosed previously in this disclosure. However, some notabledifferences exist. The BCF 3300 is larger than the CORF 300 indimensions.

As can be seen in the view of FIG. 16, the BCF 3300 includes an overhangportion 3367 that extends rearwardly from a lip feature 3555 which issimilar to lip feature 1555 except that the overhang portion 3367extends rearwardly from lip feature 3555. The overhang portion 3367 isconnected to the lip feature 3555 as a further stress reduction featureto reduce the concentration of stress on particular elements of the BCF3300. As can be seen with further review of FIG. 15, the BCF 3300generally follows the contour of the leading edge 170 as withembodiments elsewhere in this disclosure and in the disclosure ofapplication for U.S. patent bearing Ser. No. 13/839,727.

A golf club head 4100 includes a BCF 4300 as shown with reference toFIG. 17. With reference to FIG. 18, the BCF 4300 includes an overhangportion 4367 that extends rearwardly from a lip feature 4555 which issimilar to lip feature 3555. The overhang portion 4367 is connected tothe lip feature 4555 as a further stress reduction feature to reduce theconcentration of stress on particular elements of the BCF 4300. As canbe seen with further review of FIG. 17, the BCF 4300 generally followsthe contour of the leading edge 170 as with embodiments elsewhere inthis disclosure and in the disclosure of application for U.S. patentbearing Ser. No. 13/839,727. A weight pad 4350 can be seen partially inthe view of FIG. 18 and is similar in shape and size to the weight pad1350 as described previously within this disclosure. As seen withreference to FIG. 19, the BCF 4300 extends to a height 4472 above the GPthat is about 14.0 mm in the current embodiment. The height 4472 isabout the same as the height 2472, and one of skill in the art wouldunderstand that the dimension variants of height 2472 would apply toheight 4472 as well.

As noted previously in this disclosure, the BCFs disclosed hereinmanipulate the boundary conditions to provide altered spin profiles forgolf shots in accord with the current disclosure.

The distances as measured in various tests as described in the currentdisclosure are based on finite element analysis (FEA) simulations. Ingeneral, test parameters for both FEA and robot testing are set up thesame. For fairway wood-type and hybrid-type golf club head testing andanalysis, the test is setup having impact conditions of 107 mph clubhead speed, 4° de-lofting at impact, 0.5° downward path, and 0°scoreline relative to ground (score lines parallel to ground plane).This is experimentally verified with similar setup conditions in themethodology as follows. Utilizing a robot and a head tracker to set upthe club for a center face shot. The impact conditions are 107±1 mphclub head speed, 4±1° de-lofting, 0±1° scoreline lie angle relative toground, 2±1° open face angle relative to target line, 2±1°inside-to-outside head path, and 0.5±1° downward path. For driver-typegolf club head testing and analysis, target club head speed is 107 mph,0° delofting, 0.5° downward path, and 0° scoreline relative to ground.For robot testing related to driver-type golf club head testing, impactconditions are 107±1 mph club head speed, 0±1° delofting, 0±0.5°scoreline relative to ground, face angle to target of 1.5°-2.0°, headpath 1.5°-2.0° inside-to-outside, and −1°-0° downward path. For thepurposes of this disclosure, the term “impact loft” can be described ashead static loft minus delofting. As such, for a fairway wood type golfclub head of about 15° static loft with about 4° delofting in FEAanalysis, the impact loft is about 11°. Similarly, for a driver-typegolf club head having 11° static loft and 0° delofting, the impact loftis about 11°. For the sake of robotic testing, impact loft is the loftof the golf club head as measured at impact. In various testing, dynamiclofting may occur. Depending on how far the CG of the golf club head isfrom the SA, dynamic loft may have a material impact on the impact loftof the test. For example, in various embodiments, if the golf club headis of about 15° static loft with about 4° delofting for the testconditions specified above, dynamic lofting may cause variance in theimpact loft of the golf club head such that the impact loft of the testis greater than 11°. For example, if dynamic lofting added 2°, the netimpact loft would be 13° instead of 11°. As such, for FEA testing,dynamic lofting is not considered, and impact loft is merely the staticloft minus delofting. For robot testing, impact loft is the actual loftat impact factoring in static loft, test protocol delofting, and dynamiclofting.

Once the robot is set up to achieve the desired head impact conditions,the ball is placed on a tee for center face impact within ±1 mm. Atleast 10 shots are taken at the center face, and the average distance ismeasured (both carry and total). The average carry for center face iscalled DC_(CF) and the average total distance for center face is calledDT_(CF). Next, the tee is moved to another impact location (i.e., 5±1 mmheel of center face), and 10 more shots are taken with the average carryand total distance measured. The average carry for 5 mm heel is calledDC_(5H) and the average total distance for center face is calledDT_(5H). This is repeated for each of the other impact locations wherethe average carry and total distance are measured based on at least 10shots from each of these tee positions and the same head presentation asfor the center face shot. These are called DC_(5T) and DT_(5T) for 5 mmtoe, DC_(5A) and DT_(5A) for 5 mm above center face, and DC_(5B) andDT_(5B) for 5 mm below center face). After measuring average distancesfor each of the impact locations, the carry range, DC_(RANGE), (maximumaverage carry−minimum average carry) are determined, and the totaldistance range, DT_(RANGE), (maximum average total−minimum averagetotal) are calculated. Furthermore, the standard deviation of carry,DC_(SDEV), is calculated from DC_(CF), DC_(5H), DC_(5T), DC_(5A) andDC_(5B); the standard deviation of total distance, DT_(sDEV), iscalculated from (DT_(CF), DT_(5H), DT_(5T), DT_(5A) and DT_(5B)). Invarious tests, such analysis and testing can be performed starting fromthe balance point instead of center face if the two are different. Invarious embodiments, various tests may follow the same protocol from thebalance point—the projection of the CG onto the face. However, unlessnoted otherwise, data in this disclosure is measured using the testprotocol with respect to the CF and not the balance point.

A suitable robot may be obtained from Golf Laboratories, Inc., 2514 SanMarcos Ave. San Diego, Calif., 92104. A suitable head tracker is GC2Smart Tracker Camera System from Foresight Sports, 9965 Carroll CanyonRoad, San Diego, Calif. 92131. Other robots or head tracker systems mayalso be used and may achieve these impact conditions. A suitable testinggolf ball is the TaylorMade Lethal golf ball, but other similarcommercially available urethane covered balls may also be used. Ingeneral, similar commercially available golf balls are within similarspecifications. As such, similar commercially available urethane coveredballs include a polyurethane outer cover of a thickness between0.02-0.05 inches and a Shore D hardness between 50 and 65; at least twolayers, wherein at least one layer is a core; a PGA compression of75-100; a diameter between 1.670-1.690 inches; and a mass between 45-46grams, all ranges being inclusive. In various embodiments, the COR ofthe ball at 125 feet per second V_(in) is 0.800-0.820 inclusive,although such COR need not be within the range cited above for all testball embodiments. In various embodiments, COR of the ball may bedifferent from the range noted above. In most embodiments, at least onelayer is an ionomer mantle layer; in most embodiments, the core is apolybutadiene core, although various resin-based core materials mayperform similarly to polybutadiene core materials. All balls used fortest must be commercially available and USGA conforming. The preferredlanding surface for total distance measurement is a standard fairwaycondition. Also, the wind should be less than 4 mph average during thetest to minimize shot to shot variability.

Table 1 includes FEA simulation data as indicated above. The data ofTable 1 analyzes the golf club heads of the current disclosure ascompared to golf club heads in the industry, particularly one embodimentof application for U.S. patent bearing Ser. No. 13/839,727 asimplemented into the TaylorMade JetSpeed fairway wood. Each golf clubhead of Table 1 was set up with a loft of 14.6°, face angle of 1.0°open, club head speed of 107.0 mph. Data were measured at center face. 5mm above center face, and 5 mm below center face.

TABLE 1 Ball Launch Speed Angle Spin Carry Total COR [mph] [deg] [rpm](yds) (yds) JetSpeed @ CF 0.82 149.62 10.57 2808 237.68 257.8 JetSpeed 5mm low 0.789 150.01 9.13 3638 232.34 248.62 JetSpeed 5 mm high 0.8146.08 11.61 2543 233.15 254.79 Golf Club Head 0.823 150.12 10.55 2707238.84 259.8 1100 @CF Golf Club Head 0.804 151.19 8.92 3567 234.76 251.51100 5 mm low Golf Club Head 0.8 146.32 11.7 2403 233.7 256.5 1100 5 mmhigh Golf Club Head 0.832 150.9 10.61 2448 240 263.5 4100 @CF Golf ClubHead 0.814 152.03 9.23 3145 238.8 257.7 4100 5 mm low Golf Club Head0.804 146.78 11.62 2314 233.9 257.8 4100 5 mm high

As can be seen, each of the golf club heads of the current disclosuredecreased spin on all comparable shots. Additionally, COR was higher atmost locations, resulting in increased ball speed. As a result, shotsstruck with the various golf club heads traveled longer total distancethan the comparable JetSpeed golf club head.

Table 2 includes robot test data setup as indicated above. Golf clubhead 1100 was of 15° loft angle. Golf club head 4100 was of 15° loftangle. The reference club—a TaylorMade JetSpeed fairway wood—was of14.5° loft angle. All head speeds were between 106.5 mph and 107.9 mphat testing.

TABLE 2 Ball Launch Speed Angle Spin Carry Total [mph] [deg] [rpm] (yds)(yds) JetSpeed @CF 151.6 11.6 3915 236.6 248.3 JetSpeed 5 mm low 150.09.49 4419 226.9 238.9 JetSpeed 5 mm high 150.7 13.2 3232 244.1 257.6JetSpeed 5 mm heel 147.8 11.6 4101 226.7 238.3 JetSpeed 5 mm toe 147.412.2 4141 226.4 237.4 Golf Club Head 1100 152.5 11.1 3239 244.1 259.4@CF Golf Club Head 1100 152.0 8.93 3696 236.5 251.7 5 mm low Golf ClubHead 1100 151.0 12.4 2646 246.3 264.8 5 mm high Golf Club Head 1100147.9 11.1 3333 235.2 250.7 5 mm heel Golf Club Head 1100 150.6 11.43034 237.8 254.6 5 mm toe Golf Club Head 4100 152.44 11.1 3103 244.4260.7 @CF Golf Club Head 4100 152.0 12.3 3454 238.0 254.6 5 mm low GolfClub Head 4100 151.9 9.04 2588 245.6 264.5 5 mm high Golf Club Head 4100147.1 10.7 3294 233.0 249.5 5 mm heel Golf Club Head 4100 151.6 10.73107 237.3 254.4 5 mm toe

In various live player tests, a group of ten golfers, each having a USGAhandicap index of 0.0-5.0, stuck shots with the golf club heads of thecurrent disclosure and with at least one reference golf club head. Eachgolfer struck ten total shots with each golf club head and eachreference golf club head. The test was performed by striking 5 shotswith the same golf club head at a time, then striking 5 shots withanother golf club head chosen at random.

In the test of the current example, two reference clubs were used andincluded the TaylorMade Burner fairway wood from 2008 (Burner '08) andthe TaylorMade JetSpeed fairway wood along with golf club head 1100 andgolf club head 4100.

Averages were determined as reproduced in Table 3.

TABLE 3 Initial Ball Speed Backspin (mph) (rpm) Burner ‘08 142.6 4361JetSpeed 148.3 3373 Golf Club Head 1100 148.6 2567 Golf Club Head 4100149.7 2595

A similar player test was performed with driver-type golf club heads ofthe current disclosure, including golf club heads 2100 and 3100, ascompared to the JetSpeed driver as a reference club. The player test wasset up as indicated previously with respect to golf club heads 1100 and4100. All driver-type golf club heads tested were of static loft of10.7°.

Averages were determined as reproduced in Table 4.

TABLE 4 Initial Ball Speed Backspin (mph) (rpm) JetSpeed 153.0 2601 GolfClub Head 2100 153.1 2576 Golf Club Head 3100 153.8 2136

As can be seen from simulation, robot, and player testing data, BCFs ofthe current disclosure substantially decreased spin rates for similarshots in similar conditions. In various embodiments, COR increased ascompared to reference clubs. In various embodiments, ball speedincreased as compared to reference clubs. In the measurements of Table4, impact loft was about 11±1°.

The golf club heads were tested for COR as indicated below withreference to Table 5. COR data was gathered at the balance point(projection of CG onto the face 110). Then data was taken at pointsmoving out from the balance point. The data set includes points±7.5 mmand ±15 mm heelward and toeward from the balance point wherein heelwardis positive and toeward is negative. The data set includes points±5 mmfrom the balance point and −10 mm from the balance point whereincrownward is positive and soleward is negative. Additionally, the dataset includes points that are located ±10 mm heelward and toward from thebalance point and ±5 mm crownward and soleward of the balance point.Measurements were made on the TaylorMade JetSpeed fairway wood as areference club as compared to golf club heads 1100 and 4100. The data issummarized below with reference to Table 5.

TABLE 5 COR at x-axis, z-axis JetSpeed/ Golf Club Golf Club (as measuredfrom BP) Reference Head 1100 Head 4100 Balance Point (0,0) 0.809 0.8170.819 +7.5, 0 0.787 0.799 0.786 −7.5, 0 0.788 0.800 0.795  +15, 0 0.7430.731 0.743  −15, 0 0.742 0.768 0.745   0, +5 0.788 0.789 0.813   0, −50.784 0.806 0.806   0, −10 0.761 0.788 0.780  +10, +5 0.745 0.765 0.752 −10, +5 0.747 0.766 0.760  +10, −5 0.737 0.760 0.764  −10, −5 0.7380.777 0.766

Although various points are taken for the data of Table 5, more or fewerpoints may be taken as needed to determine more with more specificitythe COR data for any golf club head. COR data for various golf clubheads of the current disclosure is also seen with reference to FIG. 20A.Similar to the data of Tables 1 and 2, the data for FIG. 20A covered areference club; the reference club was a TaylorMade JetSpeed fairwaywood of about 15° static loft. Similarly, data was gathered for golfclub head 1100 and golf club head 4100. Golf club head 1100 is coveredin the data of FIG. 20B. Golf club head 4100 is covered in the data ofFIG. 20C. All clubs tested with respect to FIGS. 20A-20C were of about15° static loft.

Data regarding COR of the various golf club heads is aggregated withreference to FIGS. 20A-20C. For any area of the face 110, golf clubheads 1100 and 4100 tend to have higher COR as compared to the JetSpeedreference club. Each band of FIGS. 20A-20C represents the approximatemargin of the COR annotated. For example, for all area inside a bandannotated as “0.8,” the COR of the golf club head is at least 0.800.Understanding the size of each COR band aids in understanding the areaof the golf club face that is above a certain COR.

However, the shapes of the COR bands are not perfectly circular.Although COR area can likely be calculated by interpolation software, anexact measure of the face area above a certain COR may be difficult toaccomplish. As such, an approximation of COR area can be taken.

In order to determine an approximation of the COR area for any band, afirst extent of the band is taken parallel to the z-axis, and a secondextent of the band is taken parallel to the x-axis. The first extent andsecond extent are maximum dimensions of the shape for which the COR isat least the required number. From each of the first extent and thesecond extent, a circle is made using each extent as a diameter. Thearea of each circle is calculated, and an average of the areas of thetwo circles provides an approximation of the area within the band, alsoknown as an equivalent area and represented as Area_(Equivalent).Formulas representing the procedure above are provided below. For thesake of the formulas, the first extent is annotated as Z_(Extent) andthe second extent is annotated as X_(Extent).

${Area}_{Equivalent} = \frac{{Area}_{Z - {Extent}} + {Area}_{X - {Extent}}}{2}$wherein${Area}_{Z - {Extent}} = {\pi \left( \frac{z_{Extent}}{2} \right)}^{2}$${Area}_{X - {Extent}} = {\pi \left( \frac{x_{Extent}}{2} \right)}^{2}$

As seen with particular reference to FIG. 20A, a first extent 4004 and asecond extent 4006 are seen for the COR having a value of at least0.805. For the embodiment of the JetSpeed reference club, the firstextent 4004 is about 3.8 mm and the second extent 4006 is about 4.7 mmfor a COR of at least 0.805. The circular area relative to the firstextent 4004 is about 11.3 mm² and the circular area relative to thesecond extent 4006 is about 17.3 mm². An average of the two areasrepresenting an equivalent area is about Area_(Equivalent)=14.3 mm².Because such numbers are approximations, it is understood that adifference of up to 5% is within reasonable error of the measurement andcalculation methodology. Similarly, if actual COR area is known, it willbe understood that a calculation error of up to 10% is reasonable giventhe error of the measurements and calculation methodology.

With reference to FIG. 20B—which represents golf club head 4100—a firstextent 5004 of an area for which the COR is at least 0.805 is about 11.3mm and a second extent 5006 is about 9.3 mm. The circular area relativeto the first extent 5004 is about 100.3 mm² and the circular arearelative to the second extent 5006 is about 67.9 mm². As such, anaverage of the two areas representing an equivalent area is aboutArea_(Equivalent)=84.1 mm².

Similarly, with reference to FIG. 20C—which represents golf club head1100—a first extent 6004 of an area for which the COR is at least 0.805is about 8.0 mm and a second extent 6006 is about 12.2 mm. The circulararea relative to the first extent 6004 is about 50.3 mm² and thecircular area relative to the second extent 6006 is about 116.9 mm². Assuch, an average of the two areas representing an equivalent area isabout Area_(Equivalent)=83.6 mm².

With respect to the various measurements, Table 6 reproduces data of theinterpolation charts for the first and second extents of each COR foreach club, as shown.

TABLE 6 JetSpeed reference 4100 1100 COR Z_(Extent) X_(Extent)A_(Equivalent) Z_(Extent) X_(Extent) A_(Equivalent) Z_(Extent)X_(Extent) A_(Equivalent) 0.815 0 0 0 7.1 4.9 29.2 3.8 5.8 18.7 0.810 00 0 10.9 8.7 76.1 6.0 9.6 50.0 0.805 3.8 4.7 14.3 11.3 9.3 84.6 8.0 12.283.8 0.800 5.6 8.9 43.1 13.1 11.6 119.9 10.4 15.3 135.2 0.795 7.3 11.673.6 ND ND ND 12.4 17.6 181.8 0.790 8.9 13.8 105.6 ND ND ND 14.7 19.3231.3 0.780 11.6 18.2 182.8 ND ND ND ND ND ND

For Table, data points indicated with “ND” are meant to indicate that nodata is collected for the data point. For the JetSpeed reference club,“0” is included wherein no area exists wherein the COR is above 0.810 astested.

In testing, one methodology involves first finding the balance point ofthe club. Following such a determination, additional impact points thatare coaxial with the balance point can be used as measured parallel tothe x-axis and parallel to the z-axis. Tests may be performed along eachof these axes to determine most closely the extent of a range having thedesired COR. When the desired COR is determined in the ±x-axis and±z-axis directions, these values may be substituted for the Z_(Extent)and X_(Extent) values to determine A_(Equivalent). In many embodiments,the determined value will be within 10% measurement and calculationerror of the actual value.

The embodiment shown in FIG. 21 includes an adjustable loft, lie, orface angle system that is capable of adjusting the loft, lie, or faceangle either in combination with one another or independently from oneanother as described in detail in U.S. Pat. No. 7,887,431, entitled“GOLF CLUB,” filed Dec. 30, 2008, which is incorporated by referenceherein it its entirety. A shaft (not shown) is inserted into the sleevebore and is mechanically secured or bonded to the sleeve 3204 forassembly into a golf club using a golf club head 5100, which may be agolf club head of the current disclosure (golf club head 100, 1100,2100, 3100, 4100). The sleeve 3204 further includes an anti-rotationportion 3244 at a distal tip of the sleeve 3204 and a threaded bore 3206for engagement with a screw 3210 that is inserted into a sole opening3212 defined in the golf club head 5100. The anti-rotation portion 3244of the sleeve 3204 engages with an anti-rotation collar 3208 which isbonded or welded within a hosel 3150 of the golf club head 5100.Although not shown, the shaft and a grip may be included as part of thegolf club assembly 3500. For example, a first portion 3243 of the sleeve3204, the sleeve bore 3242, and the shaft collectively define alongitudinal axis 3246 of the assembly. The sleeve 3204 is effective tosupport the shaft along the longitudinal axis 3246, which is offset froma longitudinal axis 3248 of the by offset angle 3250. The longitudinalaxis 3248 is intended to align with the SA (seen in FIG. 7, forexample). The sleeve 3204 can provide a single offset angle 3250 thatcan be between 0 degrees and 4 degrees, in 0.25 degree increments. Forexample, the offset angle can be 1.0 degree, 1.25 degrees, 1.5 degrees,1.75 degrees, 2.0 degrees or 2.25 degrees. The sleeve 3204 can berotated to provide various adjustments to the golf club assembly 3500.In various embodiments, the sleeve 3204 may be mechanically fastenableto the golf club head 5100 to secure the shaft in a variety of positionsrelative to the golf club head 5100, thereby altering at least one ofthe loft angle, lie angle, and face angle of the golf club head 5100. Invarious embodiments, the sleeve 3204 may be secured to the hosel or toanother portion of the golf club head 5100 depending on arrangement. Oneof skill in the art would understand that using mechanical methods wouldbe considered fastening to the hosel. In various embodiments, mechanicalfastening may include, a variety of connection mechanisms, includingscrews, various threading arrangements, velcros and similar systems, andthe use of glues and various other permanent fastening methods, amongothers. One of skill in the art would understand that the systemdescribed with respect to the current golf club assembly 3500 can beimplemented the various embodiments of golf club heads (1100, 2100,3100, 4100) of the current disclosure.

Because the BCFs of the current embodiment include through-slotembodiments (providing a void in the golf club body), it is advantageousto fill the BCFs with a plugging material to prevent introduction ofdebris and to provide separation between the interior and the exteriorof the various golf club heads of the various embodiments. The pluggingmaterials disclosed in application for U.S. patent bearing Ser. No.13/839,727 are generally suitable for BCFs of the current embodimentsand are incorporated herein by reference.

In various embodiments, the plugging material may be replaced with aplug such as plug 6400, shown in FIGS. 22A-22D. As seen, the plug 6400includes an inner side 6402 and an outer side 6404. Although the outerside 6404 appears to be concave, the plug 6400 is arranged in a golfclub head such as golf club heads 1100 and 2100 such that the outer side6404 is in communication with the outside and the inner side 6402 isbonded within the BCF 1300 and 2300, respectively. The plug 6400includes a first wall 6406 and a second wall 6408. The second wall 6408is spaced from the first wall 6406. An outer surface 6409 is designed tobe bonded to the vertical surface 385 in the BCFs 1300,2300 using DP-420adhesive, although various types of adhesives may be used and would beknown to one of skill in the art. Although the plug 6400 that is shownin the current embodiment is designed for use with BCFs 1300,2300 ofgolf club heads 1100,2100, one of skill in the art would understand thatminor modifications could be made for use with the various BCFs of thecurrent disclosure and with various embodiments of CORFs in relateddisclosures that are incorporated by reference herein.

The plug 6400 of the current embodiment is made of a polyurethanematerial. In various embodiments, thermoset or thermoplasticpolyurethane may be used for the plug 6400. In various embodiments,multi-material construction may be used. In various embodiments, variousplastics, rubbers, foams, and other similarly pliable material may beused. Similar to previously noted for plugging materials, the plug 6400is designed to provide minimal interference with the deflection andmovement of the BCFs of the current disclosure. In various embodiments,simply filling BCFs of the current disclosure with plugging materialsmay have a material impact on COR of the golf club head, providingadverse response as compared to a golf club head including a BCF thatdoes not include a plugging material. The construction and materialcomposition of the plug 6400 allows the plug 6400 to deformsubstantially without significant load being placed on the BCFs or golfclub heads of the current disclosure when deformation occurs upon impactwith a golf ball. As such, the plug 6400 does not significantly restrictthe COR of the golf club heads of the current disclosure.

One should note that conditional language, such as, among others, “can,”“could,” “might,” or “may,” unless specifically stated otherwise, orotherwise understood within the context as used, is generally intendedto convey that certain embodiments include, while other embodiments donot include, certain features, elements and/or steps. Thus, suchconditional language is not generally intended to imply that features,elements and/or steps are in any way required for one or more particularembodiments or that one or more particular embodiments necessarilyinclude logic for deciding, with or without user input or prompting,whether these features, elements and/or steps are included or are to beperformed in any particular embodiment.

It should be emphasized that the above-described embodiments are merelypossible examples of implementations, merely set forth for a clearunderstanding of the principles of the present disclosure. Any processdescriptions or blocks in flow diagrams should be understood asrepresenting modules, segments, or portions of code which include one ormore executable instructions for implementing specific logical functionsor steps in the process, and alternate implementations are included inwhich functions may not be included or executed at all, may be executedout of order from that shown or discussed, including substantiallyconcurrently or in reverse order, depending on the functionalityinvolved, as would be understood by those reasonably skilled in the artof the present disclosure. Many variations and modifications may be madeto the above-described embodiment(s) without departing substantiallyfrom the spirit and principles of the present disclosure. Further, thescope of the present disclosure is intended to cover any and allcombinations and sub-combinations of all elements, features, and aspectsdiscussed above. All such modifications and variations are intended tobe included herein within the scope of the present disclosure, and allpossible claims to individual aspects or combinations of elements orsteps are intended to be supported by the present disclosure.

That which is claimed is:
 1. A golf club head comprising: a golf clubbody including a crown, a sole, and a skirt connected between the crownand the sole, the golf club body including a front including a leadingedge and a back including a trailing edge; a face connected to the frontof the golf club body, the face including a geometric center defining anorigin of a coordinate system, the coordinate system including an x-axistangential to the face and generally parallel to a ground plane; ay-axis orthogonal to the x-axis and generally parallel to the groundplane; and a z-axis orthogonal to both the x-axis and the y-axis andorthogonal to the ground plane; a boundary condition feature (BCF)located in the sole of the golf club head proximate the leading edge,the BCF being a softening BCF and including an aperture from an exteriorof the golf club head to an interior of the golf club head, the BCFincluding a plugging material to cover the aperture, the BCF extendingsubstantially from the sole into the skirt of the golf club head, theBCF having a length measured parallel to the x-axis of between about 75mm and about 95 mm; and, the sole of the golf club head including afirst sole portion located between the leading edge and the BCF, thefirst sole portion including a lip feature defining a forewardmost edgeof the BCF, the lip feature being of a thickness greater than the firstsole portion.
 2. The golf club head of claim 1, wherein the BCF includesa central point of the forewardmost edge, a first central end point ofthe forewardmost edge, and a second central end point of theforewardmost edge, the first and second central end points defining theend of a central portion of the BCF, wherein the central point isfurther from the leading edge as measured parallel to the y-axis thanthe first and second central end points.
 3. The golf club head of claim1, wherein the BCF includes a central portion, a toeward return portion,and a heelward return portion, wherein each of the toeward returnportion and the heelward return portion is defined entirely within theskirt.
 4. The golf club head of claim 1, wherein the BCF is defined bythe forwardmost edge and a rearwardmost edge, wherein a distance betweenthe forwardmost edge and the rearwardmost edge proximate center face isbetween about 4 mm and about 7 mm as measured in a direction parallel tothe y-axis.
 5. The golf club head of claim 4, wherein the BCF includes acentral portion, and wherein the distance between the forwardmost edgeand the rearwardmost edge is consistent along the entirety of thecentral portion.
 6. The golf club head of claim 1, further comprising astiffening BCF being on of defined in and connected to the crownproximate the face.
 7. The golf club head of claim 1, wherein the lengthof the BCF measured parallel to the x-axis of between about 80 mm andabout 85 mm.
 8. The golf club head of claim 1, wherein the golf clubhead includes a static loft of greater than 14°.
 9. The golf club headof claim 1, wherein the golf club head is of a volume of greater than425 cc.
 10. A golf club comprising: a golf club body including a crown,a sole, and a skirt connected between the crown and the sole, the golfclub body including a front including a leading edge and a backincluding a trailing edge, and a hosel connected to the golf club body;a face connected to the front of the golf club body, the face includinga geometric center defining an origin of a coordinate system, thecoordinate system including an x-axis tangential to the face andgenerally parallel to a ground plane; a y-axis orthogonal to the x-axisand generally parallel to the ground plane; and a z-axis orthogonal toboth the x-axis and the y-axis and orthogonal to the ground plane theface also including at least one score line; at least one BCF being oneof connected to and defined in the golf club head proximate the face; ashaft having a first end and a second end, the first end connected tothe hosel; a grip connected to the second end of the shaft, wherein as aresult of a robot test of the golf club using a urethane cover golf ballhaving at least three pieces, a spin rate of the golf ball is notgreater than 3,300 rpm, the robot testing is performed at a golf clubhead speed of 107±1 mph club head speed, 11±1° dynamic loft, 0±1°scoreline lie angle relative to ground, 2±1° open face angle relative totarget line, 2±1° inside-to-outside head path, and 0.5±1° downward path,the golf club head impacting the golf ball at centerface.
 11. The golfclub head of claim 10, wherein the first end of the shaft is connectedto a shaft sleeve and wherein the shaft sleeve is fastened to the hosel.12. The golf club head of claim 11, wherein the sleeve is fastenable tothe hosel in a variety of positions, wherein at least one of the varietyof positions is of distinct loft from at least one other of the varietyof positions.
 13. The golf club head of claim 10, wherein the golf clubhead includes a static loft of greater than 14°.
 14. The golf club headof claim 10, wherein the golf club head is of a static loft of at most14°.
 15. The golf club head of claim 10, wherein the golf club head isof a volume of greater than 425 cc.
 16. A golf club comprising: a golfclub body including a crown, a sole, and a skirt connected between thecrown and the sole, the golf club body including a front including aleading edge and a back including a trailing edge, and a hosel connectedto the golf club body; a face connected to the front of the golf clubbody, the face including a geometric center defining an origin of acoordinate system, the coordinate system including an x-axis tangentialto the face and generally parallel to a ground plane; a y-axisorthogonal to the x-axis and generally parallel to the ground plane; anda z-axis orthogonal to both the x-axis and the y-axis and orthogonal tothe ground plane the face also including at least one score line; ashaft having a first end and a second end, the first end connected tothe hosel; a grip connected to the second end of the shaft, wherein as aresult of a robot test of the golf club using a urethane cover golf ballhaving at least three pieces, a spin rate of the golf ball is notgreater than 3,300 rpm, the robot testing is performed at a golf clubhead speed of 107±1 mph club head speed, 11±1° dynamic loft, 0±1°scoreline lie angle relative to ground, 2±1° open face angle relative totarget line, 2±1° inside-to-outside head path, and 0.5±1° downward path,the golf club head impacting the golf ball at centerface.
 17. The golfclub head of claim 16, wherein the spin rate is not greater than 3,000rpm.
 18. The golf club head of claim 16, wherein the spin rate is notgreater than 2,800 rpm.
 19. The golf club head of claim 16, wherein thespin rate is not greater than 2,600 rpm.
 20. The golf club head of claim16, wherein the spin rate is not greater than 2,400 rpm.
 21. The golfclub head of claim 16, wherein the spin rate is not greater than 2,200rpm.